Health

Which case has ‘super immunity’? – VnExpress


Two new studies published in the New England Journal of Medicine show that people recovering from Covid who receive the Pfizer vaccine will significantly reduce the risk of reinfection, can create “super immunity” that neutralizes many strains.

Research published on February 16 provides further insight into the concept of “hybrid immunity”. These are people who have had immunity from natural Covid-19 infections and vaccinations.

The first study took place in Israel from March 1 to November 26 last year with 149,000 participants. Scientists have shown that people who have recovered from Covid-19 but have not been vaccinated are four times more likely to be re-infected than people who have recovered and been vaccinated.

They also found that the effectiveness of the Pfizer vaccine decreased in people over 65 years of age. Specifically, in the 16 to 64 year old group, the vaccine was 82% effective. For people 65 years of age and older, the vaccine provides 60% protection.

The study showed that the effectiveness of the vaccine did not differ between the F0s who received one and two doses. This is consistent with previous work showing that one dose of the vaccine is enough to protect people who have had Covid-19 from re-infection.

Shane Crotty, a virologist and professor of the Center for Infectious Diseases and Vaccines at the La Jolla Institute for Immunology, said the new findings have implications for vaccination policy. US officials can ask people who have been infected with nCoV to get a dose of the vaccine.

Ronen Arbel, research lead and expert at Clalit Health Services, believes that countries should adopt the same policy as Israel in March 2021: encouraging one dose of vaccine for people who have recovered from Covid-19.

“Having Covid-19 is like being vaccinated once. You should still get vaccinated, but just one more time is enough, like a booster dose,” Mr. Arbel said.

Medical staff in the US prepare a booster dose of Covid-19 vaccine. Photo: NY Times

A second study conducted in the UK showed that people infected with nCoV before receiving the Pfizer vaccine had longer-lasting immunity. The scientists used data from the SIREN study on healthcare workers. More than 35,000 volunteers were followed between December 7, 2020 and September 21, 2021. They do a PCR test every two weeks.

In the group of volunteers who did not have Covid-19 before vaccination, two doses of the vaccine were 85% effective for two months. However, the number dropped to 51% after 6 months. People with Covid-19 and vaccinated, vaccine maintain 90% protection for more than a year after initial infection, 6 months after vaccination.

The risk of re-infection of people vaccinated with Covid-19 and contracting Covid-19 was 86% lower than that of people who only got sick and did not receive the vaccine. Thus, infection with nCoV alone does not confer sustained immunity.

Dr. Monica Gandhi, associate dean of HIV, Infectious Diseases and Global Medicine at the University of California, San Francisco, said: “Exposure to the entire body of the virus (when infected with Covid-19) can stimulated general immunity, plus the enhanced response after vaccination induces superimmunity.”

According to Professor Crotty, hybrid immunity allows the body to produce more diverse amounts of antibodies, which can neutralize too many types of mutations. This is similar to a full vaccination followed by a booster shot. But hybrid immunity builds up much faster, especially in infected people who are vaccinated immediately.

Thuc Linh (According to CNN)

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