Coronavirus: “Immune weakness?” Experts say the term leads to a misunderstanding of the COVID-19 vaccine

The idea of ​​weakening immunity has gained momentum in recent weeks, and some countries are using it to justify deploying a third COVID-19 vaccine booster in the population. .. However, immunologists say that this concept is largely misunderstood.

Antibodies, proteins produced after infection or vaccination that help prevent future invasion from pathogens, level off over time, experts say it should happen.

And that doesn’t mean we aren’t protected from COVID-19.

Jennifer Gommerman, an immunologist at the University of Toronto, said the term “weakened immunity” gives people a misunderstanding of how the immune system works.

“Decrease has this implication that something is wrong and not,” she said. “It’s normal for the immune system to make large amounts of antibodies and cause a reaction in which many immune cells proliferate, and so far, such things are taken over.

“But it has to contract, otherwise you have no room for a subsequent immune response.”

Stephen Carfoot, an associate professor of immunology at the University of Western, said antibody levels rise “when the immune system is charged and ready for attack” during the “primary reaction” stage after vaccination or infection. Said.

After that, they diminish from that “emergency stage,” he added. However, the memory of the pathogen and the body’s ability to react to it remain.

B cells that make antibodies and T cells, which limit the ability of the virus to cause serious damage, work together to stop serious illness even after the vaccine is given, according to Kirfoot. T cells cannot recognize the virus directly, but they can determine which cells are infected and kill them quickly.

Recent studies suggest that T cell responses are still strong months after COVID-19 vaccination.

“You can get mild infections … (but) all those cells are still there, so they have a very stable effect on the prevention of serious illnesses,” Carfoot said. Says.

A pre-print study published this week by Public Health England suggested that protection against hospitalization and death remains much higher than protection against infection, even among older people.

Therefore, the concept of weakened immunity depends on whether it measures protection against infection or serious illness, Carfoot said.

Ontario reported 43 breakthrough cases in the hospital, compared to 256 in-hospital infections that were fully vaccinated on Friday. That day, there were a total of 795 new cases in the state, 582 of those who were not fully vaccinated or whose vaccination status was unknown.

Meanwhile, in British Columbia, 53 fully vaccinated COVID-19 patients have been hospitalized in the last two weeks, compared to 318 unvaccinated patients.

“You’ll hear people say that vaccines aren’t designed to prevent infections, but to prevent serious illnesses,” Carfoot said. “I don’t necessarily say it’s a vaccine designed to do either … it’s how the immune system works.”

This week, Moderna released real-world data suggesting that the vaccine is 96% effective in preventing hospitalization and that 87% of the more contagious Delta variants are effective in preventing infection. This is a reduction from the 94% efficacy seen in clinical trials. last year.

Moderna CEO Stephane Bancel said Dip “shows the effects of weakened immunity and supports the need for boosters to maintain a high level of protection.”

Pfizer-BioNTech claims the same with its own data, and a U.S.-based Food and Drug Administration advisory board said on Friday a third dose to people over the age of 65 or at high risk for serious illness. Decided to approve.

However, the panel rejected boosters for the general public, saying that pharmaceutical companies provided little safety data on extra jabs.

Gommerman stated that the efficacy data presented by Moderna did not indicate the need for a third dose.

“The fact that it protects 87 percent from infections is incredible,” she said. “Most vaccines can’t achieve that.”

According to Bansel, Modana’s study has not yet been peer-reviewed, but suggests that booster doses may also prolong the duration of the immune response by re-elevating neutralizing antibody levels.

However, Dr. Sumon Chakrabarti, an infectious disease doctor in Mississauga, Ontario, said looking at antibody responses alone is misleading and can be misused as a justification for a myriad of boosters.

Israel, which started a third dose for its citizens, recently talked about giving a fourth dose in the near future.

“This idea of ​​weakening immunity has been abused and I’m really worried about seeing it,” Chakrabalti said. “There is this idea that antibodies mean immunity, and that’s true … but the background levels of immunity, those of durable T cells, are not fully emphasized.”

Some experts claim that boosters for the general public are premature, but some individuals agree to benefit from a third jab.

The National Advisory Board on Immunization recommends immunodeficiency boosters that do not initiate a strong immune response from the two-dose series.

Other experts argue that long-term care residents who were prioritized when the deployment began last December may soon need a third dose. According to an English study, the group under the age of 65 may have weakened immunity, but not so much, if any.

Chakrabalti said the reduced protection of older people may be due to “overlapping factors” such as the generally weak immune system and the group living conditions of caregivers.

“These are the people at the highest risk of hospitalization,” he said. “(The length of time that has passed since taking) could play a role? Yeah, maybe.”

The duration of the immune response to COVID-19 vaccination is not yet known, but Gommerman said that immune cells normally remain in the bone marrow and produce small amounts of antibodies for “decades.”

“And if they encounter a pathogen, they can be mobilized immediately,” she said.

This report by Canadian Press was first published on September 19, 2021.