“A year ago I participated in the vaccine tests at Moderna to see if it was safe. Now, when I complete a year since a vaccination, I am happy to share that I just received a second dose. This experiment will show whether vaccines adapted to the new strains increase immunity and are safe, “wrote Haydon, who specializes in communication at the University of Washington, in his Twitter account last Saturday (3).
“It is still unclear whether this new version is really going to be necessary, but it is being developed and tested so that we can have an option,” Haydon told CNN , by phone.
Doctors are concerned that the coronavirus that causes Covid-19 may follow the dynamics of the influenza virus, which provides new vaccines each year, and this is because both the circulating strains resolve mutations quickly and the vaccine’s immunity soon.
Although early evidence suggests that vaccine immunity against Covid-19 provides lasting protection, vaccine manufacturers have already started testing and producing new versions of the immunizers targeting the most worrying variants of the virus, including strain B.1.351 , seen for the first time in South Africa, and which, in laboratory tests, carries within itself a mutation that appears to circumvent the immune response of the human body.
Pfizer’s latest report shows that people vaccinated in the African country after receiving doses of their vaccine remained protected even after a new outbreak became dominant. This corroborates laboratory experiments that argue that the immunizing agent generates an immune response so strong to the coronavirus that it also ends up protecting against mutations.
“A vaccine still has enough response to provide good protection,” said Scott Hensley, an immunologist and vaccine specialist at the University of Pennsylvania.
Despite this, vaccine manufacturers do not want to take risks. The research Haydon is participating in includes not only a third dose of the modern vaccine vaccine modified specifically to combat the South African variant, but also a third dose of the original vaccine in some volunteers. The idea is to know if the immune response reinforced by the original third dose also guarantees an advantage and is safe.
In a report released in March, a Pfizer required people who received two doses of their immunizer to remain with strong immune protection for at least six months. Researchers have struggled to say that this does not mean that immunity will end after six months, but that more extensive research has reached that conclusion at least for this period. Immunity is likely to last much longer, explains Hensley.
“I would not be surprised if we concluded that even a year after vaccination there will still be a strong response from the immune system”, he points out. “I wouldn’t even be surprised if we had to be vaccinated just once to do so.”
If that happens, the vaccine against a Covid-19 would be more like measles immunizers than flu vaccines. In the case of measles, protection lasts for life in 96% of cases.
The protection required by the two doses of Pfizer vaccine still pending 91% even after six months, according to the company. The company released more details in a statement, but not in a traditional scientific publication, and the data covers only a few people. But if it persists, it will be an indication that Pfizer and Moderna vaccines elicit long-lasting immune responses, experts say.
Hensley says the technology used by both vaccines – using messenger RNA, or mRNA – is especially potent.
“The responses elicited by these mRNA vaccines are incredibly high. What we know from animal testing of other mRNA vaccines is that the immune responses are very potent and do not diminish over time, ”said Hensley, whose laboratory has been testing mRNA vaccines for years.
Although vaccines against a Covid-19 are still new, since the virus has only been around since the end of 2019, an mRNA technology has been studied for many years, and is already used to make vaccines against influenza viruses and the causes of Ebola and Zika. Several studies have also indicated the same in relation to the new coronavirus.
In January 2021, a team led by researcher Alicia Widge, of the National Institute of Allergy and Infectious Diseases of the United States, wrote to the scientific publication New England Journal of Medicine to say that her research found that the two doses of Moderna’s vaccine produced whose decrease was discreet over time.
The vaccine also caused the body to produce T and B cells, which protect the immune system, and which they can maintain as active defenses for years. They also found that the immune response induced by the vaccine was stronger and more widespread than the immune response that follows a natural infection by the coronavirus.
Another study published in February in the New England Journal of Medicine found that blood collected from people vaccinated with the Pfizer / BioNTech immunizer continued to produce an immune response also against a South African variant.
“Although we still don’t know exactly what level of neutralization is required to protect against disease or contamination by coronavirus, our experience with other vaccines tells us that a Pfizer vaccine is likely to offer relatively good protection against this variant,” says Scott Scott Weaver, director of the Institute of Human Infections and Immunity, Texas Medical University.
However, in March, South African virologists argued that there is growing evidence that vaccines under development do not work as well against B.1.351, and recommended that vaccine manufacturers start changing their formulas now.
Although clinical tests require localized blood sampling to check immunity, Haydon barely understands how well he is protected from the virus.
“I know that at the beginning of the test, I and all the other participants developed the neutralizers. That was clear many months ago, but the level of and how that level has changed over time is not something that has not been said, ”said Haydon. “This is one of the main factors that are involved in the study”.
Haydon had a strong reaction after the first round of vaccination, and also had some effects after taking the third dose. “I ended up with fever, chills, a little nausea and a headache,” he said.
Immunologists explain that this is a sign that the immune system is responding to the vaccine, although people who have had the vaccination are also protected. In other words, it is not because someone reacted with fever that they are more protected than those who do not have any symptoms.
But Haydon knows that he cannot behave as if he is completely immune. Therefore, he wears a mask whenever he leaves the house and avoids traveling. “We are living in a world in which most people have not yet been vaccinated. The fact that I have been vaccinated myself does not change like things for me ”, explains the volunteer, who said that he takes many of the same precautions as one that has not yet been vaccinated.
Although the possibility of having to look for a hospital on account of Covid-19 is very small, Haydon can still spread the virus, which is a concern. “Only very well-known data are emerging that show that vaccinated people transmit the virus less. So this is also a very good discovery ”.
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