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: Garrett Aitken/iStock/Getty Images Plus via Getty Images – A ‘triangle test’ involves mixing up two of the original products with one of the new reformulation – or vice versa – to see whether taste testers notice the difference.

Health

Controversy over Reese’s ingredients reveals standard food industry practices most consumers never notice

A family fight over Reese’s ingredients reveals how often food companies quietly change recipes.

Good Partner

4/6/2026

Jonathan Deutsch

Springtime in Pennsylvania is peanut butter egg season. This year some consumers may taste the eggs a bit more critically and scrutinize the ingredients and label more carefully.

Reese’s, a Hershey brand, is known for combining chocolate and peanut butter in delicious and iconic ways. Reese’s products come in a variety of formats, called “line extensions.” These include everything from peanut butter chips for baking and chocolate peanut butter popcorn for snacking to limited-time offers for holidays – such as the popular Reese’s Peanut Butter Eggs for Easter.

On Feb. 14, 2026, Brad Reese, grandson of the founder, issued an open letter criticizing the Hershey Company for introducing line extensions – in this case, mini hearts for Valentine’s Day, with the flavors familiar to Reese’s lovers but made with cheaper ingredients, such as “chocolate candy” and “peanut butter creme.”

Ingredients like these seem similar but do not meet the FDA standards of identity for milk chocolate and peanut butter, the key components of the original Reese’s cups. For example, the FDA standard for milk chocolate requires at least 10% chocolate liquor.

Hershey responded in a statement: “As we’ve grown and expanded the Reese’s product line, we make product recipe adjustments that allow us to make new shapes, sizes and innovations that Reese’s fans have come to love and ask for, while always protecting the essence of what makes Reese’s unique and special: the perfect combination of chocolate and peanut butter.”

I am a certified research chef and food and hospitality professor in Philadelphia, where I founded the Drexel Food Lab, a culinary innovation and food product development lab. I am also a huge fan of Reese’s Peanut Butter Cups. When my older daughter was a toddler, learning her colors and shapes, I trained her to organize her trick-or-treat loot by separating the orange squares for dad.

As someone with decades of experience in product formulation, I am not surprised that the ingredients for some Reese’s products have changed over the years. One of my first jobs as an intern in corporate R&D was formulating cost reductions for existing products and later developing cost-effective line extensions building on the brand equity of the original product. What Hershey is doing with the Reese’s brand is Consumer Packaged Goods Marketing 101.

Reese’s recently introduced some variations of its classic peanut butter cups that use ‘chocolate candy’ compound coatings and ‘peanut butter creme’ instead of real chocolate and peanut butter. AP Photo/Gene J. Puskar

How food manufacturers deal with rising costs

Much has changed in the marketplace since Reese’s Peanut Butter Cups were developed by H.B. Reese in 1928 in Hershey, Pennsylvania, about two hours northwest of Philadelphia.

Inflation, tariffs, labor costs, fuel costs, employee benefits, competition and the vulnerability of climate-threatened crops, such as cacao, vanilla and sugar – none of which are produced anywhere near Pennsylvania – have made the confectionery business increasingly challenging.

When faced with rising costs, food manufacturers have three options:

1. Shrink the product. Reese’s Peanut Butter Cups have gradually shrunk from 0.9 ounce in the 1980s to 0.75 ounce today. That’s a 17% reduction. This phenomenon has been dubbed “shrinkflation.”

2. Raise prices. There is certainly a market for premium peanut butter cups, but how much will a consumer pay for the Reese’s brand? $5? $10? I suspect most consumers expect a single serving to be a couple of bucks at most.

3. Lower costs. While the company can improve operational efficiencies, changing the formula to reduce or eliminate high-cost ingredients is a standard industry practice to keep prices consistent for consumers in the midst of a dynamic supply chain. This phenomenon has been dubbed “skimpflation” and is Brad Reese’s main complaint.

Reformulations are common in the food industry. In addition to prices rising in general, a supplier could go out of business or have a shortage. A regulatory change or shift in consumer sentiment might prohibit the use of an ingredient. Wars, tariffs or climate change can raise costs temporarily or permanently.

Reformulations can be done well

Sensory and food science tools that we teach in our Drexel culinary and food science programs help ensure little market disruption and a consumer mostly unaware of the changes.

For example, a consumer discrimination test that food product developers love is a called the triangle test. Two samples from the original formula and one sample from the new formula – or vice versa – are presented to the consumer. If the consumer can identify the different one, the product developer did a poor job in preserving the beloved brand through the reformulation. But if consumers can’t tell the difference, the reformulation may be able to move forward.

In 1998, Frito-Lay reformulated some of its signature products using a synthetic fat called olestra – with the brand name Olean – that could cause unpleasant side effects, including anal oil leakage. John T. Barr/Hulton Archive via Getty Images

Sometimes product developers get it wrong in introducing a new formulation. Some of us are old enough to remember Crystal Pepsi, the McLean Deluxe burger or Doritos made with olestra. These products failed, respectively, due to lack of defined consumer benefit, misalignment with the brand, and bad press due to digestive side effects.

But most reformulations go unnoticed – the good work of food technologists who strive to keep food safe, affordable and delicious for consumers.

So, are these new Reese’s products inferior to the original? Maybe. Like with taste in art or wine, if it tastes good to you, it’s good. If not, vote with your wallet, or send the company a note like Brad Reese did.

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

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Researchers are blowing people’s minds after revealing the ideal shower length

“In general, you really only need soap in your armpits, your groin, and your feet.”

GOOD Staff

Adam Albright-Hanna

4/5/2026

Some doctors now believe you should be spending even LESS time in the shower than previously thought. Admittedly, I was already shocked when I found out a while back that the average shower should take only eight minutes. But upon reflection, it made sense. While hot showers can feel relaxing, we obviously need to be conscious of our resources, no matter where we live in the world.

But a recent piece by Pang-Chieh Ho called “You Could Be Showering Too Long,” published in Consumer Reports, claims that showers should really only be around five minutes, seven at the most. Just shaving off a couple of minutes can help tremendously with conservation. “For people in the U.S., the average shower lasts about 8 minutes, according to the Environmental Protection Agency. That’s 20 gallons for every average shower, given that the standard showerhead uses around 2.5 gallons of water per minute.”

Experts say your shower might be too long

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And it’s not just because of the environment. Our skin can dry out more quickly than some might think. Dermatologist Lisa Akintilo, MD, is cited as saying, “It’s true that long, hot showers may feel restorative, but they can dry and irritate the skin.”

An article in Time magazine, “How Much Do You Actually Need to Shower?” by Angela Haupt, reveals that some doctors say you can skip even the five-minute daily shower, though they admit, “there’s no one-size-fits-all equation.” Dermatologist at NYU Langone Health, Dr. Mary Stevenson, suggested, “Ideally, I think people should shower at least every other day. Most people, by day two or day three, are not clean. But it’s a little bit personal.” She later added, “In general, you really only need soap in your armpits, your groin, and your feet.”

“You probably don’t need to be in the shower as long as you are. You’re no cleaner—it’s just for your psychological health or for your routine.”

– Philadelphia dermatologist Dr. Jules Lipoff

Some people on Reddit disagree. In a thread called “On average, how long do you take to shower?” many admitted that long showers are a guilty pleasure. A few people answered 45 minutes to an hour. One even claimed they showered for “light years,” though someone quickly pointed out that “light year” was a measurement of distance, not time.

@themakeshiftproject
HOW LONG IS TOO LONG?? Shouldn’t Be Longer Than 5 Minutes! #fyp #shower #routine #bathroom #people #clean
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One noted that there are variables in play. “Depends on how many shower beers.”

Another measures the length of time in music. “Two Spotify songs,” they insisted.

People online still love their long showers

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One Reddit user got vulnerable about the mental benefits of a hot shower. “The mean and the median probably differ quite a lot for me. The vast majority of my showers do not exceed 20 minutes, but I’ve had some depression showers or anxiety showers or whatever you wanna call them where I stayed in for over an hour.” Another commenter put it less delicately: “Until I can no longer feel the pain of life.”

And lastly, this person didn’t mince words but mentioned the temperature variable. “If it’s a hot shower, no less than 30 minutes. If it’s a cold shower, I scrubba dubba the F out of there in less than three.”

This article originally appeared two years ago. It has been updated.

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Happiness expert’s refreshing take that the best friendships are useless

“If you want to be happier you need more useless.”

Mark Wales

4/3/2026

As Americans have become more tribal, isolated, and downright lonely, the need for quality friendships is at an all-time high. Yet, some of the most important relationships begin when we aren’t looking for them. Sometimes something seemingly insignificant, like a simple hobby or a mutual love, slowly grows into a real connection.

Dr. Arthur Brooks shared his insights into friendships on the Mighty Pursuit podcast. He explains that there are three types of friendships, and the one that matters most is a useless friendship.

Aristotle believed friendship was the secret to happiness

(Discussion begins at 1 hour into the video.) Brooks traces the value and importance of friendship back to the famous philosopher Aristotle. He explains that Aristotle believed the ultimate secret behind a happy life was friends. Brooks says, “In the Nicomachean Ethics, he [Aristotle] said there’s three levels of friendship that bring more happiness. And if you get stuck at lower levels, it’s going to be a problem for your life.”

The first type of friendship is transactional. These are people with whom you do business or have a casual acquaintance. You don’t really know them on a personal level. The relationship is friendly, but if business or a reason for interacting stops, so does the friendship.

Brooks describes transactional friendships, saying, “There’s nothing wrong with it, it’s just incomplete.” He continues, “If that’s all you have you’re going to be hopelessly lonely.”

The second type is friendships of beauty. They are chosen out of admiration. These are people we want to be around. Brooks describes it as, “You’re magnetic. It could be because of your physical beauty, your sense of humor, your intelligence, or your success.”

Relationships built on admiration are better than transactional, but Brooks warns, “If that beauty goes away, so does that friendship.”

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Useless friends are the best

Aristotle described the friendship that brings the most satisfaction as Atelic, meaning it has no specific end or goal. Brooks calls it “Useless. It’s cosmically, beautifully useless. And so if you want to be happier, you need more useless people you just love.”

Describing the characteristics of this type of friend, Brooks shares, “you’re walking together, shoulder to shoulder, into the future and looking at something you both love mutually.” He continues, “There’s always a third love in these perfect friendships.”

Examples offered by Brooks might be a couple loving their children or best friends who love a sports franchise. Brooks says, “It can be dumb, or it can be cosmic. But the whole point is that third love is the glue that makes that, that useless relationship beautiful and perfect to you.”

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Science loves a useless friendship

Research supports Aristotle’s belief that having a friendship without an agenda makes for a richer and happier life. A 2023 study in Frontiers found that friendships valued for the stimulating companionship and shared activities predicted higher well-being, life satisfaction, and personal growth. Best friends aren’t based on networking or usefulness.

A 2024 study in the National Library of Medicine found that high-quality best friendships lowered loneliness and boosted self-esteem. Meaningful relationships can begin with a shared love, but over time, become a part of who the friends actually are.

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A 2022 study at Cornell University revealed that repeated physical proximity and similar interests strongly increased the likelihood of friendship formation regardless of background or social differences. Activities like walks, hobbies, sports, and creative interests offered a shared space where even unlikely friendships grow.

Brooks suggests the most important friends come from connecting over the smallest things. They don’t happen because we need them; more so, they exist for their own sake. These “useless friendships” are grounded in mutual joy and common loves. They may seem small or incidental at first, but the Atelic relationship shapes our happiness the most.

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