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Dr. Topham weighs in Covid questions put forth to Bloomberg Prognosis reporters and editors in this edition of Covid Daily.

As more states expand eligibility and vaccination rates continue to rise, pre-pandemic normalcy is on the horizon. The question now on many people's minds is how long vaccines will provide protection. While the short answer is it's too soon to know with certainty, experience with other infectious diseases can help scientists make an educated guess. And it is good news -- your immune system will probably be able to detect and quickly respond to the coronavirus for many years.

"Long-term data from vaccinated individuals will give us the definitive answer, but all signs point to the fact that a level of protection from vaccines should last for a significant period of time, potentially two to three years or longer," said David Topham, Ph.D., the director of the University of Rochester Medical Center Translational Immunology and Infectious Diseases Institute. Topham and his colleagues at URMC have decades of experience studying the immune response to respiratory infections. His work on this subject has been featured recently in The Washington Post and The Wall Street Journal.

One of the sources of uncertainty is the simple fact that currently approved COVID vaccines are new, so researchers don't have hard data on the durability of immunity to the virus. While around 100 million Americans have received at least one dose, the bulk of these vaccinations have only occurred in the last couple of months. However, data from a smaller group who participated in clinical trials provide some evidence that vaccines are producing a long-lasting immune response. Both Moderna and Pfizer-BioNTech recently announced that their vaccines remain 91% effective in preventing infection, and 100% effective in preventing severe disease six months after the second dose.

How long does protection from Covid vaccines last? It's a question that's becoming more important as some of the first people to be vaccinated approach four months post-inoculation.

The short answer is: We don't fully know yet. But more data is coming in that provides clues. Here's what we know so far.

How long are we protected from getting Covid-19? Does the efficacy decline over time?

Recent data from Pfizer, the manufacturer of one of the three vaccines available in the U.S., indicates that protection lasts at least six months. The results showed minimal antibody decline. Recipients of the Moderna vaccine also had robust levels of antibodies more than six months later, according to a recent study published in NEJM.

Some people have incorrectly concluded that means that those vaccines offer only six months of protection, says Scott Hensley, a professor of microbiology at the University of Pennsylvania. "That's false," says Dr. Hensley. "We only have six months of data...Six months from now it's likely we'll learn we have one year of protection."

Boosters will likely be needed for at least a few years "out of an abundance of caution, knowing that immunity does wane in some individuals more than others," says David Topham, the Marie Curran Wilson and Joseph Chamberlain Wilson Professor in the Department of Microbiology and Immunology and the founding director of the Translational Immunology and Infectious Disease Institute. The article also appeared on MSN News.

Here we are, finally on the cusp of our long-awaited Hot Vaxx Summer. About 112 million people in the U.S. have received at least one dose of a COVID-19 vaccine, and if you haven't gotten one yet, chances are you will be able to soon: Starting April 19, the general public over 16 will become eligible. Among people who are enthusiastic about vaccination, there's a mix of excitement—after more than a year of living through the pandemic, some light at the end of the tunnel!—along with some nervousness about side effects. Some who have been lucky enough to be vaccinated already have reported chills, fevers, fatigue, or even vomiting after receiving a vaccine dose. (Side effects are more common after the second dose of the Pfizer or Moderna vaccines.)

As a result, people are getting all sorts of advice about what to do—or not to do—in the hours leading up to and following a COVID-19 vaccination. Slate staffers report receiving general advice, like staying hydrated or avoiding alcohol. Meanwhile, my parents were advised to adhere to a very specific routine: Drink one glass of water before the shot with three days' worth of Vitamin C supplements, then one glass of water after.

Other advice, especially around taking over-the-counter painkillers like ibuprofen or acetaminophen has been contradictory.* One friend told me the nurse who administered her shot told her to take ibuprofen afterward; meanwhile, on social media, people have posted about taking pain meds even before their vaccination appointment, in hopes it could head off soreness at the injection site or muscle aches. But others tell me they've heard to specifically avoid ibuprofen and use acetaminophen instead, or advised to avoid pain killers entirely. What does the science say?

To understand that, it's worth reviewing what vaccines actually do. While the Pfizer and Moderna vaccines use a different method from Johnson & Johnson's vaccine, the result is the same: The vaccine teaches your immune system to recognize coronavirus. In that process, your body recruits specific types of cells to identify and clean up invader cells. One type of cell, called helper T-cells, aids another, called B-cells, which release antibodies that target coronavirus. Essentially, the vaccines serve as a rehearsal for your immune system to practice how to spot and clear coronavirus cells, so that if it encounters the real thing, it's ready.

But if you do end up taking over-the-counter painkillers with your vaccine—or already did—it's probably not a huge deal. The overall effect of NSAIDs is likely pretty small. Among the small body of existing studies looking at the effect of NSAIDs on post-vaccine antibody production in children, researchers did find some evidence of reduced antibody responses, but that did not affect the efficacy of vaccines. A 2009 paper examining the effect of OTC painkillers in mice and human cells in a lab found a similar result: Ibuprofen, but not acetaminophen, dampens antibody responses. But, of course, humans are not mice, and our cells may behave differently when they're actually inside of us rather than in a petri dish. "This is not an FDA-sanctioned clinical trial that shows [NSAIDs] have an effect on vaccinations, which is what you really need to do," says David Topham, a co-author of that study and a professor of microbiology and immunology at the University of Rochester. "I think if they did the trial, the effect would be modest." Still, based on his results, Topham says that if he had a choice, he'd take acetaminophen and not ibuprofen. And, if it makes you feel any better, Shresta told me she actually caved and took some ibuprofen the day after her second vaccine dose. "I had a major deadline the next day and with the headache, there was no way that was going to happen," she says. Life happens.

Seniors across the country are rightly enraged that they were promised a 21-day interval between vaccine doses only to have that appointment pushed into July due to new recommendations by the National Advisory Committee on Immunization prescribing a four-month interval between doses. Seniors, after all, were the most vulnerable to COVID-19.

Throwing thousands of Canadian seniors into three extra months of vaccine limbo was never going to be popular, particularly when Canada is the only jurisdiction on Earth to use a four-month interval between doses.

That controversy is not going to abate anytime soon, but below find the best arguments as to why Canada's decision to stretch its booster shot gap could end up saving lives.

In a pandemic that has been defined by near-constant government missteps, this may be one of the few times where Canada has prioritized science over political expediency.

The 21-day gap between doses was always somewhat arbitrary

There is no spreadsheet at Pfizer headquarters saying that 21 days is the optimum, experiment-tested gap to maximize the effectiveness of their vaccine. In fact, it's a number largely pulled out of thin air.

"I know this sounds crazy, but it's arbitrary. If you look for literature that documents why that's the best time point, there isn't any," David Topham, a University of Rochester immunologist, said in a February interview.

In fact, the typical rule of thumb is that booster shots have the best potency when administered at least two months after the initial dose. Vaccinations for HPV, Hepatitis A and Hepatitis B, among others, all have their boosters at five months or more . Boosters shots for avian flu, meanwhile, have been found to be more effective at six months than if given only 28 days after the first shot, according to a 2009 study .

You may be among the more than 95 million people in the United States who have taken at least one dose of a coronavirus vaccine. Or you may still be awaiting your turn. Regardless, there's a crucial question on most of our minds: How long will the vaccine really protect us?

As with most aspects of the virus, the answer is not completely clear. Why? Because although we have been battling the pandemic for more than a year, the vaccines were granted emergency use authorization relatively recently. So experts have not had time to observe their long-term effectiveness.

However, that research is underway, and in the meantime, experts say we can make an educated guess.

Can we extrapolate from what we know about natural immunity?

In fact, much of this hypothesizing comes from extrapolating data examining immune responses in people who have had covid-19 and illnesses from other coronaviruses, rather than in people who have been vaccinated, said Dbeibo, who is director of vaccine initiatives for Indiana University.

"But vaccine responses should not be less reliable than in natural infection," she added.

Current research shows that people who have been infected with covid-19, the illness caused by the coronavirus, retained immunity that was robust after eight months. That gives researchers a starting point in predicting how long immunity may last after vaccination, Dbeibo explained.

But research also shows people who had more severe cases developed a stronger immune reaction than those with milder forms of the disease. And because vaccine-induced immunity appears to be more similar to natural immunity that is derived from severe covid-19 infections, researchers say they believe people who take a coronavirus vaccine will be protected better than most people with natural immunity, said David Topham, a professor of microbiology and immunology at the University of Rochester.

All of that said, antibodies will wane. And although it is a gradual process, once antibodies decline to a level that is no longer protective, reinfection is possible. Still, the infection is likely to be milder, experts said.

Topham, founding director of the Translational Immunology and Infectious Disease Institute at the University of Rochester, has been studying the coronavirus and the role of memory B cells — immune cells that persist for a lifetime and produce antibodies when re-exposed to a pathogen that they have been programmed to fight. He said some people who were hospitalized with severe covid-19 infections still had high frequencies of memory B cells, as well as antibodies, up to nine months after infection.

He said memory B cells can even adapt quickly to a new variant, usually within days.

The University of Rochester Medical Center (URMC) and Rochester Regional Health (RRH) have begun a new clinical trial that will evaluate the safety and efficacy of a third dose of the Pfizer/BioNTech COVID-19 vaccine. The vaccine is currently approved for a two dose regimen. This study represents an important step in the development of long-term vaccination strategies, including the creation of booster doses that target coronavirus variants.

"While widespread vaccination is the key to moving past the current health crisis, COVID-19 has the potential to become a seasonal and mutating virus," said Ed Walsh, M.D., and infectious disease specialist at URMC. "This study will help us understand important questions about the safety and immunogenicity of multiple doses of an mRNA vaccine, information that could ultimately enable us to extend the protection of vaccines and develop tailor-made, variant-specific boosters."

URMC and RRH have been involved in the development of the Pfizer/BioNTech vaccine since the launch of phase 1 clinical trials in May 2020 when volunteers in Rochester were among the first in the nation to receive the then experimental vaccine. Rochester was also a site for the phase 2/3 clinical trials that ultimately led to the vaccine's emergency use authorization (EUA) by the U.S. Food and Drug Administration last December. Since then, tens of millions of people across the globe have received at least one dose of the Pfizer/BioNTech vaccine.

The new study will involve individuals who participated in the phase 1 trials last spring, all of whom were fully vaccinated more than 6 months ago. Over the next several weeks, researchers will dose 144 volunteers, including 35 in Rochester, with a booster dose of the EUA-approved Pfizer/BioNTech vaccine. Rochester is one of four sites in the U.S. involved in the study.

The local studies are led by Walsh and Ann Falsey, M.D.; both hold faculty appointments in the URMC Department of Medicine, Infectious Diseases and are members of the Infectious Disease Unit at RRH. Pfizer contracted with URMC to conduct the clinical trial in Rochester and the recruitment of study volunteers and testing of the vaccine will occur at Rochester General Hospital.

While the duration of protection provided by the Pfizer/BioNTech vaccine is unknown, it is assumed that immunity wanes over time, a phenomenon common in vaccines for other infectious diseases. The trial will measure the boost to the immune system and evaluate in the lab whether antibodies and other immune cells generated after the third dose provide protection against coronavirus variants. The study will also seek to answer is how well a third dose of the vaccine is tolerated in healthy volunteers and researchers will closely monitor participants for side effects.

The findings of the study will also be important as vaccine developers have turned their focus to the development of vaccines that can be tailored to meet the threat of emerging strains of the virus. Pfizer and BioNTech announced today that the companies had begun discussions with regulatory agencies regarding an early stage clinical study to evaluate a modified version of approved vaccine.

"While we have not seen any evidence that the circulating variants result in a loss of protection provided by our vaccine, we are taking multiple steps to act decisively and be ready in case a strain becomes resistant to the protection afforded by the vaccine. This booster study is critical to understanding the safety of a third dose and efficacy against circulating strains," said Albert Bourla, Chairman and Chief Executive Officer, Pfizer. "At the same time, we are making the right investments and engaging in the appropriate conversations with regulators to help position us to potentially develop and seek authorization for an updated mRNA vaccine or booster if needed."

URMC co-authored study indicates that breastfeeding is safe for COVID positive mothers

A study conducted by researchers at the University of Rochester Medical Center (URMC) -- in collaboration with several other universities - indicates that breastfeeding women with COVID-19 do not transmit the SARS-CoV-2 virus through their milk, but do confer milk-borne antibodies that are able to neutralize the virus.

Drs. Bridget Young, Kirsi Jarvinen-Seppo and Antti Seppo were part of the breast milk research team

The study, "Characterization of SARS-CoV-2 RNA, antibodies, and neutralizing capacity in milk produced by women with COVID-19," published on February 9 in the journal mBio -- analyzed 37 milk samples submitted by 18 women diagnosed with COVID-19. None of the milk samples were found to contain the virus, while nearly two thirds of the samples did contain two antibodies specific to the virus.

Critically, this study provides evidence that COVID-19 positive mothers should not be separated from their newborn children. At the onset of the pandemic, major health organizations have often provided contradictory advice on whether this separation was necessary. This report will hopefully offer new clarity on guidance for post-natal mothers.

"We only want to sequester a mother from her baby if it's medically necessary," said co-investigator Bridget Young, Ph.D., assistant professor in the Department of Pediatrics at URMC, "However, the issue was very confusing for practitioners who don't have sufficient evidence. These early results suggest that breast milk from mothers who have had a COVID-19 infection contains specific and active antibodies against the virus, and that they do not transfer the virus through milk. This is great news!"

URMC was funded over $130,000 by the Bill and Melinda Gates Foundation for this research. The initial study published in mBio reported on the first group of 18 women who submitted milk samples. Results from the larger study will be forthcoming, which will hopefully reinforce the initial findings, according to Young.

The URMC research group is led by Antti Seppo, Ph.D., in the Department of Pediatrics. Other co-investigators include Casey Rosen-Carole. M.D., medical director of lactation services and programs at URMC, and Kirsi Jarvinen-Seppo M.D., Ph.D., research associate professor in the Department of Pediatrics.

Mark Sangster, PhD, and David Topham, PhD, both research professors in the Department of Microbiology and immunology, did the primary work measuring antibody assay levels in their lab.

"We found high levels of IgA -- a common antibody in blood and other body fluids -- in their breast milk. IgAs migrate in mucosal transfer, therefore this is encouraging information that mothers transfer these antibodies," said Sangster.

The full research team also included scientists from the University of Rochester School of Medicine and Dentistry, Brigham and Women's Hospital and Harvard Medical School, and the University of Idaho. The team now has enrolled nearly 50 women who were diagnosed with COVID-19 and has followed their progress with the disease for as long as two months.

The study was initiated to address the lack of existing research into COVID-19 in breastmilk. The next steps will be to see if the initial results are replicated in larger samples.

"This work needs to be replicated in larger cohorts. Additionally, we now need to understand if the COVID-19 vaccine impacts breast milk in the same way," said Young.