“A year ago, I tried the Modern vaccine to see if it was safe. (Spoiler: Yeah!) Now, on my #COVIDvacina birthday, I am happy to share that I just received a third dose. This booster experiment will reveal (1 ) whether vaccines adapted to the strain increase immunity and (2) whether they are safe, “said Haydon, a communications expert at the University of Washington, via Twitter last Saturday.
“It is not clear whether this new adjusted version is really necessary,” Haydon told CNN in a telephone interview.
Doctors are concerned that the coronavirus could end up being like the flu, which requires a new vaccine each year, both because circulating strains mutate rapidly and because the immunity of the vaccine decreases rapidly.
“It’s still compatible enough to have good protection,” said Scott Hensley, an immunologist and vaccine specialist at the University of Pennsylvania.
But vaccine makers aren’t taking any chances. The trial Haydon is participating in is testing not only a third dose of the Modern vaccine adjusted to specifically protect against B.1.351 – that’s what he got – but a third dose of the original vaccine on some volunteers as well, to see if the answer Enhanced immune is safe and offers an advantage.
A report released last month by Pfizer suggests that people receiving both doses maintain strong immunity for at least six months. Experts have been working hard to point out that this does not mean that immunity ceases in six months. This means that the longer test volunteers were followed up to see what their immunity is. It is likely to last much longer, said Hensley.
“I wouldn’t be surprised if we knew a year from now that these vaccines are still producing a strong immune response,” Hensley told CNN.
“I would not be surprised if this is a vaccine that we received only once.”
This would make the vaccine more like measles vaccines than flu vaccines. Measles vaccination protects against infection for life in 96% of people.
Protection against Pfizer’s two-dose vaccine remains above 91% even at six months, according to the company. The details were released in a statement, not in a formal scientific publication, and the data covers only a few thousand people. But if it persists, it is an indication that the Pfizer and Moderna vaccines elicit a long-lasting immune response, experts say.
Hensley says the technology used by both vaccines – delivery of genetic material known as mRNA messenger RNA – is especially potent.
“The antibody responses elicited by these mRNA vaccines are incredibly high. What we know in animal models with other mRNA vaccines that have been tested previously – we know that these antibody responses are incredibly long-lasting and do not decrease over time,” said Hensley , whose laboratory has been testing experimental mRNA vaccines for years.
Although coronavirus vaccines are new – the virus has only been around since the end of 2019 – mRNA technology has been studied for many years and used to make vaccines against influenza, Ebola and Zika viruses.
Several studies have indicated this with the coronavirus vaccine.
Another study published in the New England Journal of Medicine in February showed that blood collected from people who received the Covid-19 vaccine from Pfizer / BioNTech continued to produce an immune response against B.1.351.
“Although we do not yet know exactly what level of neutralization is needed to protect against Covid-19 disease or infection, our experience with other vaccines tells us that the Pfizer vaccine is likely to offer relatively good protection against this new variant,” Scott Scott Weaver, director of the Institute of Human Infections and Immunity at the University of Texas Medical Branch, told CNN at the time.
Although he is participating in clinical trials that require regular blood samples to check his immunity, Haydon has no idea how well he is protected from the virus.
“I know that at the beginning of the trial, me and all the participants developed neutralizing antibodies – the kind you’re looking for. That was clear many, many months ago,” said Haydon. “But the level of these antibodies, and how the levels have changed over time, is not something I was told. That is one of the main things that are being evaluated throughout the study.”
He had a strong reaction to the first round of vaccination and said that the third dose he just received had some effects as well.
“Flulike is the right way to describe my symptoms,” he said. “I ended up with fever, chills, a little nausea, a headache,” he added.
Immunologists say it is a sign that the immune system is responding to the vaccine, although people who do not report any symptoms also develop an immune response, so the symptoms do not seem to suggest that someone is having a better response than someone who has not developed fever.
Haydon doesn’t know if his answer this time says anything about the level of immunity he has had since the first dose he received a year ago.
What he does know is that he cannot behave as if he is completely immune. For this reason, he still wears a mask whenever he leaves and avoids almost all trips.
“We are living in a world where most people are not vaccinated. The fact that you have been vaccinated yourself does not change everything for you,” said Haydon.
“We still have to take many of the same precautions as an unvaccinated person,” he added. Although the risk of going to the hospital is very low, spreading the virus is a major concern. It wasn’t until recently that we started collecting data (showing) that vaccinated people also spread the virus much less. So this is a recent discovery and a very good sign. “