Vaccine reinforcement protects even those who have already caught Covid – 03/10/2023 – Health

The protection of four doses of the vaccine against a serious infection caused by the omicron variant of the coronavirus reached more than 90%, even in people who had a previous infection.

Defense was also higher in people who had a previous infection of the coronavirus with BA.1 and BA.2 variants (89.5% and 94.3%), respectively.

When considering those people who had never had Covid, the effectiveness of two doses of immunizers (that is, the recommended primary scheme, without reinforcement) was 41.5% against infection by BA.5. In people who had a confirmed case in the past, protection was 50% and 53.1%, respectively, in those who had a previous infection with BA.2 and BA.1 against the severe condition caused by the BA.5 variant.

The data are from a study published this Friday (10) in the specialized medical journal Jama Network Open. Research reinforces the importance of booster shots to protect against new infections of the virus and against serious cases, even in people who have had Covid in the past.

To assess the so-called real-life efficacy (or effectiveness) of omicron vaccines, the scientists analyzed 3,415,980 positive case records from August 1 to August 31, 2022, with the peak of new infections for the BA variant. 5, with the same number of negative cases. Records were adjusted for gender (53.9% of cases were women), age (mean age of participants was 40.2 years), place of residence, and previous health conditions.

The so-called vaccination status (how many doses each person had received) of the participants was considered as a variable for the analysis of effectiveness.

The researchers then calculated what would be the odds ratio (OR or odds ratio, in English) of having an infection by the BA.5 variant in people who already had a previous infection or not and, in a second moment, if this new infection would be serious or not.

With this value for each variable (previous infection and vaccination status) they calculated the effectiveness of the vaccine. In addition to the values ​​mentioned above, the analysis found the effectiveness of 90.9% of protection against severe infection in individuals with four doses of the vaccine without a previous picture of Covid, and of 93.9% and 92.9%, respectively, in those who previously infected with the BA.1 and BA.2 variant.

The conclusion of the research, according to the authors, is that taking four doses of the vaccine, regardless of the previous history of infection with the coronavirus, was associated with greater protection against the serious condition caused by BA.5.

Several studies have already pointed out that boosting the vaccine against Covid offers greater protection for serious cases and hospitalizations caused by the new variants, including those who have already had the disease.

The research reinforces, so to speak, that the so-called combined immunity, represented by immunity acquired by infection plus immunity induced by vaccination, can help in the development of mild conditions and milder symptoms even after reinfection.

Still, the protection of vaccines against the most aggravated effects of the disease helps to prevent the so-called long Covid, which can appear up to a year after infection, as indicated by the most recent research.

The expectation is that the knowledge acquired in the last three years will help to develop vaccines that are increasingly adapted to the variants in circulation and that they can add to the protection against infections.

Experts still warn of the risks of unvaccinated people or people with an incomplete vaccination schedule, in addition to those at greater risk of illness, of catching Covid and developing a serious condition.

Therefore, they say, it is essential that people update their vaccination schedule until the last booster dose offered: fourth dose for people over 40 years old, third for all people over 12 years old and the fifth dose or bivalent for groups priority and people over 60 years old, in addition to immunosuppressed and transplanted people.

The effectiveness study was conducted by researchers at the Cheongju Center for Disease Control and Prevention in South Korea and Anam Hospital at Korea University in Seoul.