The future of the pandemic It will depend, to a large extent, on the protection provided by vaccines against covid-19. It’s been a year since these injections began to build a individual and collective shield against the virus. But how strong are these defenses? How long do they last? What happens when they disappear? And do they work the same against the new variants? According to the experts, one part of these questions is still surrounded by unknowns and the other depends on the mutations, variants and lineages that the virus develops.
These are the keys to understanding what we know (and what we don’t) about the immunity that vaccines build against covid-19 and how they could turn the tide of the health crisis.
How long do covid-19 antibodies last?
According to the immunologist Julià Blanco, from IrsiCaixa, before talking about how long immunity against covid-19 lasts, we must explain the differences between infections and vaccines. The studies carried out to date suggest that the people who have passed the covid-19 produce, in general, a good level of antibodies. After three months, these thresholds drop slightly and then stabilize. Everything indicates that after a year the protection remains stable. In the vaccinated people, Instead, the antibodies begin to be produced after the first dose, reach their peak after the second puncture, and then progressively decline over about six months. The protection provided by these drugs, therefore, seems to generate a stronger but less stable immune response.
“Not all people respond the same. There are many factors that influence the production of antibodies “, clarifies the immunologist Gemma Moncunill, from the Isglobal Institute. Old people, for example, produce fewer antibodies than young women. “But the quantity of the antibodies is not everything. It is also necessary to look at the quality of the defenses and, above all, in the immunological memory”, emphasizes the scientist.
What happens when the antibodies disappear?
Both people who have had the disease and those who have received a vaccine eventually reach a point where it seems that the antibodies against covid-19 they have practically disappeared (or are at a minimum). So, explains Moncunill, the key is to look at what happens with the ‘second line of defense‘of our immune system: cellular memory. In fact, as the researcher explains, the presence of T lymphocytes and of B cells is an indicator that our immune system remembers how to deal with the virus. And this, in turn, suggests that our body has memorized instructions to fight the virus that could last for years (although it is not clear exactly how many).
If I have fewer antibodies, am I more at risk of getting infected with covid?
Everything points to the fact that, as antibody levels drop, so do decreases the effectiveness of vaccines to avoid symptomatic infections. This, in practice, means that months after the punctures increases the risk of becoming infected with coronavirus. Yes indeed. According to the studies carried out to date, even if they become infected, vaccinated people are much more protected against serious disease (and death) by covid-19. Hence the insistence of the experts of accelerate the vaccination campaign around the world.
If the defenses hold, what good are the booster doses?
The delivery of third doses against covid-19 could have both individual and collective benefits. According to Moncunill, deliver one reinforcement puncture to the elderly population it would provide more protection to a group that, in itself, suffers more comorbidities and that if they fall ill are more likely to develop a severe form of the disease.
From a collective point of view, Blanco also highlights that booster doses could help reduce virus transmission, the number of cases and, consequently, the number of people requiring medical attention or hospitalization. “This strategy would only work in the medium term. At times like now, when cases are rampant, the only way to stop the virus is to apply other measures“, emphasizes the expert.
Is it more effective to continue with the same vaccine or to mix several?
All vaccines available on the market have been shown to generate high levels of antibodies against covid-19. As Moncunill explains, mRNA vaccines, like Pfizer and Moderna, generate more antibodies than adenovirus formulas, like Astrazeneca and Janssen. Regarding the delivery of third doses, Blanco cites a recent study that points out that the mixture of vaccines generates a stronger and longer-lasting immunity. The best combination, the analysis highlights, is that of Moderna and Astrazeneca. “The amount of antibodies is fifty times higher in patients with two doses of Astrazeneca and a booster of Moderna”, the scientist comments.
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Are omicron antibodies effective?
This is one of the questions that, according to experts, could mark the future of the pandemic. The quick answer is that, as of today, it is still not entirely clear. Blanco cites recent published research on the subject and explains that laboratory studies suggest, “omicron is between 20 and 40 times more resistant to antibodies than previous variants“This, argues the scientist, would considerably increase the risk of reinfection (especially at a time when infections are rampant again).
“The good news is that, by the looks of it, the immune system continues to control the severe infection so, although the risk of reinfection increases, people who have already developed antibodies against the virus are less likely to get sick, “says Blanco.
Reference-www.elperiodico.com