How and when will we know that a COVID-19 vaccine is safe and effective?

With COVID-19 vaccines currently in the final phase of study, you’ve probably been wondering how the FDA will decide if a vaccine is safe and effective.

William Petri

Sep 23, 2020

By William Petri

September 23, 2020

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With COVID-19 vaccines currently in the final phase of study, you’ve probably been wondering how the FDA will decide if a vaccine is safe and effective.

Based on the status of the Phase 3 trials currently underway, it is unlikely that the results of these trials will be available before November. But it is likely that not just one but several of the competing COVID-19 vaccines will be shown to be safe and effective by the end of 2020.

I am a scientist and infectious diseases specialist at the University of Virginia, where I care for patients with COVID-19 and conduct research on the pandemic. I am also a member of the World Health Organization Expert Group on COVID-19 Vaccine Prioritization.

What is the status of COVID-19 vaccines in human clinical trials?

Phase 3 studies are underway for the Moderna and BioNTech/Pfizer vaccines and the Oxford/AstraZeneca viral vector vaccine.

Each of these vaccines uses the SARS-CoV-2 spike glycoprotein, which the virus uses to infect cells, to trigger the immune system to generate protective antibodies and a cellular immune response to the virus. Protective antibodies act by preventing the spike glycoprotein from attaching the virus to human cells, thereby neutralizing the SARS-CoV-2 virus that causes COVID-19.

In the case of Moderna’s nucleic acid vaccine, the messenger RNA encoding the spike glycoprotein is encased in a fat droplet – called a liposome – to protect the mRNA from degradation and enable it to enter cells. Once these instructions are inside the cells, the mRNA is read by the human cell machinery and made into many spike proteins so that the immune system can respond and begin producing antibodies against this coronavirus.

The Oxford/AstraZeneca uses a different strategy to activate an immune response. Here an adenovirus found in chimpanzees shuttles the instructions for manufacturing the spike glycoprotein into cells.

Phase 1 and 2 studies by pharmaceutical companies Janssen and Merck also use viral vectors similar to the Oxford/AstraZeneca vaccine, while vaccines by Novavax and GSK-Sanofi use the actual spike protein itself.

Animal tests show the vaccines provide protection from coronavirus infection

Studies in animal models of COVID-19 provide convincing evidence that vaccination with the spike glycoprotein will protect from COVID-19. Experiments have show that when the immune system is shown the spike protein – which alone cannot trigger disease – the immune system will generate an antibody response that protects from infection with SARS-CoV-2.

In studies in hamsters an adenovirus viral vector – the approach used by Oxford/AstraZeneca, for example – was used to immunize with the Spike glycoprotein. When the hamsters were infected with SARS-CoV-2 they were protected from pneumonia, weight loss and death.

In nonhuman primates, DNA vaccines – which deliver the gene for the spike glycoprotein – reduced the amount of virus in the lungs. Animals that produced antibody that prevented virus attachment to human cells were most likely to be protected.

What have the early Phase 1 and 2 studies in humans shown?

Overall, vaccination has triggered a more potent neutralizing antibody response than even that seen in patients recovering from COVID-19.

This has also been the case for Moderna’s vaccine currently in Phase 3 trials and for vaccines from CanSino Biologics and Oxford/ AstraZeneca.

What side effects have been observed?

Physicians have recorded mild to moderate reactions when the subjects were observed up to 28 days after vaccination. These side effects included mild pain, warmth and tenderness at the site of injection, and fever, fatigue, joint and muscle pain.

But Phase 1 and 2 studies are by small by design, with just hundreds of participants. So these trials will not be large enough to detect uncommon or rare side effects.

The emphasis on safety as the primary goal was recently demonstrated in the Phase 3 Oxford/AstraZeneca vaccine trial where one vaccinated individual developed inflammation of the spinal cord. It isn’t clear whether the vaccine caused this reaction – it might be a new case of multiple sclerosis unrelated to the vaccine – but the Phase 3 trial was halted in the U.S. until more is known.

How is the FDA ensuring that a vaccine will be safe yet quickly produced?

The FDA has issued guidance for industry on the steps required for developing and ultimately licensing vaccines to prevent COVID-19 – these are the same rigorous safety standards required for all vaccines.

There are, however, ways to speed the process of approval that are centered on “platform technology.” What this means is that if a vaccine is using an approach such as an adenovirus that has previously been shown to be safe, it may be possible for a company to use previously collected data on toxicity and pharmacokinetics to fast-track clinical trial approval.

While speed and safety may appear conflicting goals, it is also encouraging to note that the rival vaccine manufacturers have jointly pledged not to bow to any political pressures to rush vaccine approval, but to maintain the most rigorous safety standards.

How protective does a vaccine need be to receive FDA approval?

The FDA has set the bar for the primary endpoint of a Phase 3 trial of 50% protection for approval of a COVID-19 vaccine.

Protection is defined as protection from symptomatic COVID-19 infection, defined as laboratory-confirmed SARS-CoV-2 infection plus symptoms such as fever or chills, cough, shortness of breath, fatigue, muscle aches, loss of taste or smell, congestion or runny nose, diarrhea, nausea or vomiting.

This means that an effective vaccine is considered one that will reduce the number of infections in vaccine recipients by half. This is the minimal protection that is anticipated to be clinically useful. That is, in part, because lower levels of efficacy could paradoxically increase COVID-19 infections if it leads vaccinated people to decrease mask wearing or social distancing because they think they are completely protected.

Since a vaccine might be more effective at preventing severe COVID-19, the FDA instructs that protection from severe COVID-19 should be a secondary endpoint.

How many people have to be vaccinated to know if a vaccine works in Phase 3?

The current Phase 3 trials are enrolling 30,000-40,000 subjects. Most of these participants will receive the vaccine and some a placebo.

When, exactly, the results of Phase 3 studies will be released depends in large part on the rate of infection in the placebo recipients. The way that these vaccine studies work is that they test if naturally acquired new coronavirus infections are lower in the group that received the vaccine compared with the group receiving the placebo.

So while it is good news that COVID-19 infections have dropped recently in the U.S. from 70,000 to 40,000 cases per day, this drop in new infections may slow the vaccine studies.

Will Emergency Use Authorization fast-track vaccine?

In an emergency such as we are faced with the COVID-19 pandemic, with approximately 700 new deaths and 40,000 new cases per day right now, the FDA is authorized to allow the use of unapproved products for the diagnosis, treatment and prevention of disease. That includes a vaccine.

The standard approval process for vaccines can require more than one year of observation after vaccination. If the short-term safety is good and the vaccine works to prevent COVID-19, then the vaccine should be approved for use under an Emergency Use Authorization while it is still being studied.

Under Emergency Use Authorization, the FDA will continue to collect information from the companies producing the vaccines for benefit and harm, including surveillance for vaccine-associated enhanced respiratory disease or other potentially rare complications that might be observed in only one in a million.

What should we expect in terms of approvals?

I expect that the FDA will approve several vaccines by the end of 2020 under its Emergency Use Authorization authority so that vaccination can begin immediately, starting with high-risk groups including first responders, health care personnel, and the elderly and those with preexisting medical conditions.

This will be followed rapidly with roll-out of vaccination to the population at large, while all of the time the FDA and vaccine manufacturers will continue to monitor for side effects and work to improve upon these first vaccines. This process is expected to take months.

It may not be life back to normal next year, but all signs point to a healthier 2021.

William Petri is a Professor of Medicine at the University of Virginia.

This article originally appeared on The Conversation. You can read it here.

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Photo credit: Justin Paget/DigitalVision via Getty Images – Women with postpartum depression and anxiety have a higher risk of birth complications and death by suicide.

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Nearly 20% of new moms have anxiety or depression, but a promising psychedelic treatment is on the horizon

Luvesilocin could change postpartum care.

Good Partner

7/7/2026

Camille Hoffman

About 1 in 5 women will experience depression and anxiety during pregnancy or in the year after giving birth. If untreated, a mother who has these conditions has a higher risk of birth complications, overall poorer health, impaired bonding and nurturing of her infant, and a higher risk of death by suicide.

But a new treatment moving through the Food and Drug Administration clinical trials process may be key to treating, or even curing, depression and anxiety in postpartum people. It is a newly named psychedelic, luvesilocin. It functions like psilocin, the psychoactive chemical within psilocybin mushrooms. It may be able to positively affect the unique hormonal shifts, brain changes and disconnection that can lead to these conditions like no existing treatments.

In prior studies of psilocybin, researchers have observed rapid improvement in symptoms – and sometimes a cure after a single dose – of conditions such as major depression and PTSD. In a recent FDA Phase 2 study of luvesilocin, we found similar improvements in postpartum depression.

I was the site investigator for the University of Colorado, one of 35 participating sites across the U.S. The study enrolled 84 postpartum women who were within a year of giving birth and ended in May 2025.

I have spent my career as a board-certified obstetrician-gynecologist contemplating how the prenatal experience shapes lifetime health. I have also followed the psychedelic data closely. I’ve been eager to find evidence-based pregnancy and postpartum applications of psychedelics, given these drugs’ promise in treating other mental health conditions.

Depression and anxiety’s impact on moms and babies

One drug that has been studied and enhanced our understanding of the way psychedelics work is MDMA, which is commonly known as ecstasy and causes a euphoric high.

According to peer-reviewed research published by Bessel van der Kolk in 2024, MDMA can lead to improvements in individuals being able to identify, describe and feel their feelings. Other improvements resulting from MDMA assisted therapy include more self-compassion and a broader desire and capacity for connection with others.

Connection, especially the earliest one between a mother and infant, plays one of the most significant roles in providing the foundation for humans to grow and flourish. Postpartum depression is often defined by disconnection and impaired bonding.

Children born to mothers with untreated depression and anxiety have a higher risk of falling behind on early developmental milestones. They may also have behavioral concerns, such as hyperactivity or ADHD, and are more likely to withdraw from social activities. They tend to report somatic complaints, such as body aches and pains in early childhood.

Children of mothers who had depression or anxiety during pregnancy are also at risk of these same conditions as they enter their teenage years. They have nearly twice the risk of these conditions compared to teenagers whose mothers did not have untreated depression and anxiety. This pattern means depression and anxiety can become a multigenerational cycle. But this cycle can be interrupted with adequate treatment and support.

Increased levels of the hormone oxytocin were found by researchers in the blood of depression study participants who were given MDMA, LSD and mescaline, which are all psychedelic drugs. The increase in oxytocin led to more feelings of trust, empathy and connection.

Oxytocin is a hormone produced in the part of the brain called the hypothalamus and is released from the pituitary gland into the bloodstream. It plays a critical role in birth and infant feeding. It also aids in the wiring and formation of human social brains.

Oxytocin is important in maternal bonding with an infant. Conversely, early childhood stressors, such as a mother suffering from mental illness, reduces oxytocin levels in children. This may be a contributor to adverse mental and physical health outcomes later in life.

In depression studies that involved men, psilocybin did not have as great of an impact as other psychedelic medications on oxytocin production. But there is reason to believe that oxytocin may play a greater role in postpartum patients because it’s levels are higher during birth and lactation than in other phases of life.

FDA study of psilocybin-like medication

In February 2026, the FDA granted luvesilocin breakthrough therapy status. This status is used to speed up the development of promising new medications for serious or life-threatening conditions. The drug received this status because our research found meaningful and rapid reductions in depression scores in those who received the treatment.

In the Phase 2 study, 77% of postpartum women who received a psychedelic dose, 30mg of luvesilocin, had significant improvement in their postpartum depression. Overall, 71% had no symptoms of postpartum depression seven days after the psychedelic session.

The purpose of an FDA Phase 2 study is to determine the effectiveness of an experimental medication on a particular disease or condition. In this case, the study is evaluating luvesilocin’s effect on postpartum depression scores and symptoms. In the group that received the placebo, a microdose of the drug, more than half experienced an improvement in their symptoms, but most still had some symptoms after seven days.

These are much higher response and remission rates than trials of the existing medications used for postpartum depression treatment. Existing treatments include selective serotonin reuptake inhibitors, known as SSRIs, and a medication called zuranolone. The latter is the only medication to have specific FDA approval for postpartum depression.

Access to psychedelic treatments

In 2023, the Colorado legislature passed the Natural Medicine Health Act. It offers a legal pathway for people to receive natural psychedelics, such as psilocybin mushrooms, in therapeutic settings. The first natural medicine healing centers opened in early 2026. Some locations advertise treatments for everything from postpartum depression to birth trauma.

Oregon has a similar state-regulated program. Numerous other states have different pathways toward legal psychedelic-assisted therapies and decriminalization of psilocybin-assisted therapy. Nationally, there was a recent federal executive order to accelerate action on treating serious mental illnesses. The order included mention of the use of psychedelic therapies.

Looking forward

By the end of 2026, Phase 3 of the luvesilocin trial for postpartum depression is slated to begin. Phase 3 trials are conducted to confirm the effectiveness and further evaluate the overall risks and benefits of a new medication. Each phase is an important regulatory step before a medication can be approved and available in clinical settings.

In Phase 3, 200 participants with postpartum depression will be recruited across participating sites. While I’m optimistic about the potential of this research, I believe its value can be established only through rigorous blinded clinical trials, objective data analysis, and conclusions and approval that are fully supported by the evidence.

Phase 3 will also include participants who are still breastfeeding. A study of luvesilocin during lactation in healthy volunteers demonstrated very low levels passed from the mother into breast milk. Thus, this medication would be considered safe for breastfeeding.

Luvesilocin may become a game-changing postpartum depression treatment medication in just a couple more years. On a much larger scale, psychedelic medicine could elevate our collective well-being and happiness, replacing systemic cycles of depression, anxiety, trauma and isolation with connectedness and compassion. These drugs could literally rewire our approach to trauma, addiction and how we relate to one another.

This article originally appeared on The Conversation. You can read it here.

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Photo credit: AP Photo/Adam Gray – Extreme heat can become lethal quickly. A woman fans herself while waiting in line to buy Broadway show tickets during a heat advisory in New York’s Times Square in May 2026.

Health, Well-being

As a major heat wave grips the eastern US, here’s how to stay safe – and the heat stroke warning signs to watch for

Know the danger signs before heat turns deadly

Good Partner

7/7/2026
Brian Bossak

Millions of Americans are facing dangerous heat and humidity going into the July Fourth holiday as a major heat wave spreads across large parts of the central and eastern United States.

For many people, this is the time of year for cookouts, beach trips and other outdoor activities. Soccer fans are packing into stadiums for World Cup matches. But summer also brings the risk of dangerously high temperatures in many parts of America.

Cities as far north as Chicago and Detroit experienced a heat index over 100 degrees Fahrenheit (37.8 Celsius) in early July, and large parts of the East Coast, including New York and Washington, D.C., were bracing for similar conditions on Independence Day. Washington, D.C., and Philadelphia both canceled Independence Day parades and shortened or delayed outdoor gatherings, including the Great American State Fair on the National Mall, because of the extraordinary heat risk.

The NOAA Weather Prediction Center’s heat forecast, released July 1, 2026, shows the maximum heat risks states can expect to see at some point through Sunday, July 5. NOAA Weather Prediction Center

I study health risks in a warming climate as a professor of public health, and I’ve seen heat become a growing concern. In the U.S., hundreds of people succumb to heat-related illnesses each year. Older adults and people in areas that historically haven’t needed air conditioning tend to see the highest rates of illnesses during heat waves, as Chicago saw in 1995 when at least 700 people died in a heat wave.

Here are some of the key warning signs to watch for when temperatures rise – and ways to keep cool when the heat and humidity get too high.

Signs of heat-related illness to watch for

Heat-related illnesses occur across a spectrum, and mild heat stress can quickly progress to life-threatening heat stroke if a person is exposed to dangerous conditions for too long.

Mild forms of heat-related illness include heat cramps and heat rash, both of which can be caused by extensive sweating during hot conditions. Cooling the body and drinking cool fluids can help.

When heat-related illnesses progress into heat exhaustion, the situation is more serious. Heat exhaustion includes symptoms such as dizziness, nausea, excessive sweating, feeling weak, thirst and getting a headache.

Construction workers are often out in the heat for long periods of time, including during this heat wave in Los Angeles in July 2024. Etienne Laurent/AFP via Getty Images

Heat exhaustion is a signal that the body is losing its ability to maintain a stable core temperature. Immediate action such as moving to a cool, ideally air-conditioned space, drinking liquids, loosening clothes and applying wet cloths are some of the recommended steps that can help keep heat exhaustion from progressing to the most dangerous form of heat-related illness, heat stroke.

Heat stroke is a medical emergency. At this point, the body can no longer maintain a stable core temperature. A body with heat stroke can reach 106 degrees Fahrenheit or higher rapidly, and that heat can quickly damage the brain, heart and kidneys.

Signs of heat exhaustion and heat stroke, from the National Weather Service and Centers for Disease Control and Prevention. NOAA/CDC

Typically, someone suffering heat stroke has exhausted their reserves of sweat and salt to stay cool, so sweating eventually stops during heat stroke. Their cognitive ability fails, and they cannot remove themselves from danger. Heat stroke can cause seizures or put someone into a coma as their core temperature rises. If the condition is not treated immediately, and the core temperature continues to rise, heat stroke becomes fatal.

Because heat exhaustion can lead to heat stroke, addressing heat-related illnesses before they progress is vital.

How to tell when the heat is too high

Heat risk isn’t just about temperature – humidity also increases the risk of heat-related illnesses because it affects how well sweating will cool the human body when it gets hot.

Instead of just looking at temperature when planning outdoor activities, check the heat index, which accounts for heat illness risk associated with temperature and relative humidity.

It doesn’t take very high temperatures or very high humidity for the heat index to enter dangerous territory.

A heat index chart shows how heat and humidity combine for dangerous conditions. NOAA

However, the heat index is still a conservative measure of the impact of heat on humans, particularly for outdoor workers and athletes at summer practices. This is because temperature measurements used in weather forecasting are taken in the shade and are not exposed to direct sunlight. If someone is outside and exposed to the direct sun, the actual heat index can be as much as 15 F higher than the heat index chart indicates.

A more sophisticated measurement of heat effects on human health is what’s known as the wet-bulb globe temperature, which takes into account other variables, such as wind speed and cloud cover. Neither takes into account a person’s physical exertion, which also raises their body temperature, whether working at a construction site or playing soccer.

Tips for staying safe in a heat wave

How can you stay cool when heat waves set in? The answer depends in part on where you are, but the main points are the same:
- Avoid strenuous outdoor activities in high temperatures if possible. If you start to feel symptoms of heat-related illnesses, drink fluids that will hydrate you. Find shade, rest, and use cool, damp cloths to lower your body temperature. If you see signs of heat stroke in someone else, call for medical help.
- Be careful with fans. Fans can be useful if the temperature isn’t too high because they wick sweat away from the body and induce evaporative cooling. But at very high temperatures, they can accelerate heat buildup in the body and lead to dangerous conditions. If indoor temperatures reaches 95 degrees or higher, using fans can actually be dangerous and raise the risk of heat-related illnesses.
- Find a cooling center, library or community center where you can get inside and rest in an air-conditioned space in the hottest hours. In places such as Phoenix, where high temperatures are a regular hazard, cooling centers are typically opened in summer. Northern cities are also opening cooling centers as heat waves occur there more frequently than they did in the past. Urban areas with a lot of pavement and buildings – known as heat islands – can have temperatures well above the city’s average.
- Hydrate, hydrate, hydrate! Drink plenty of fluids, and don’t forget about the importance of electrolytes. Heat-related dehydration can occur when people sweat excessively, losing water and necessary salts from the body. Some sports drinks or rehydration fluids restore electrolytes and hydration levels.
Older adults and people with disabilities often face higher risks from heat waves, particularly if they can’t easily move to a cooler environment. Communities and neighbors can help protect vulnerable populations by providing cooling centers and bottled water and making regular wellness checks during high heat.

Summer can be a season of fun. Just remember the risks, keep an eye on your friends and neighbors when temperatures rise, and plan ahead so you can beat the heat.

This article originally appeared on The Conversation. You can read it here.
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Photo credit: Leigh Prather/Shutterstock.com – Dogs often react with great fear to July 4th celebrations. Border collies such as this dog are especially sensitive to loud noises.

Health, Well-being

Every dog has its day, but it’s not the Fourth of July

How to protect anxious pups from holiday booms.

Good Partner

6/25/2026
Christine Calder

The Fourth of July can be a miserable day for dogs. The fireworks make scaredy-cats out of many canines.

That’s because dogs, like humans, are hardwired to be afraid of sudden, loud noises. It is what keeps them safe. Some dogs, though, take that fear to the extreme with panting, howling, pacing, whining, hiding, trembling and even self-injury or escape. And, unlike humans, they don’t know that the fanfare on the Fourth is not a threat. Dogs hear the fireworks and process it as if their world is under siege.

How a dog responds to noises may be influenced by breed, with German shepherd dogs more likely to pace, while border collies or Australian cattle dogs are more likely to show their fear by hiding.

While we veterinarians don’t know exactly why some dogs are afraid of fireworks and others not, many dogs that react to one noise often react to others. Therefore, early intervention and treatment are essential in protecting the welfare of these terrified dogs. Here’s how you can protect your dog from fireworks.
- Take your pet to the vet. If your dog is afraid of fireworks, the first step is to have your veterinarian evaluate him or her, especially if your dog’s noise sensitivity is relatively new. One 2018 study found a link between pain and noise sensitivities in older dogs, indicating that muscle tension or sudden movements in response to a loud noise may aggravate a tender area on the body and thus create an association between the loud noise and pain, causing fear of that particular noise to develop or escalate.
- Create a “safe haven” in your home with a secure door or gate, preferably away from outside windows or doors. Close the blinds or curtains to reduce outside noises, and play some classical music to help reduce stress by creating a relaxing environment for your dog during the show. A white noise machine or box fan may also help reduce anxiety, along with a pheromone like Adaptil sprayed on bedding, a bandanna, a collar or from a diffuser plugged into the wall.
- Consider noise-canceling headphones such as Mutt Muffs to muffle the sounds and further reduce noise sensitivities.
- Find a food your pet will love. This could be cut pieces of boiled chicken or squeeze cheese. Sit with your pet and feed him with each boom. You can also use a long-lasting food-dispensing or puzzle toy to release food continuously during the show. This is to help your dog make a positive association with the noises for the future.
- Consider anxiety wraps, fabric wraps that exert a gentle pressure on your dog’s body. These may help to lower heart rate and other clinical signs of fear and anxiety, operating on the belief that they swaddle a scared animal and thus calm its fears. These work best, however, in conjunction with a complete behavior treatment plan including medication or behavior modification, or both.
- When it comes to comforting your dog, the jury is still out. It is difficult, however, to reinforce an emotional response with comfort. Therefore, it is OK to pet your dog when frightened by a noise event so long as the dog appears to be comforted and not more distressed by the attention.
This article originally appeared on The Conversation. You can read it here.
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