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Long Covid: women, reinfected and without the 4th dose are at greater risk of the condition, the study points out


On the other hand, infections with the newer variants (Delta and Omicron) resulted in fewer long-term covid cases than contaminations with the Wuhan and Gamma strains.

Have been infected twice or more by coronavirus and not having taken the fourth dose of the disease vaccine increases the risk of long covidunderlines a study conducted by the Instituto Todos pela Saúde and the Hospital Israelita Albert Einstein published this Friday 6. The work also underlines that women are more affected by persistent symptoms, although the cause of this phenomenon is not yet clear.

The results have been published in pre-printed article on the platform medRxiv and will still be reviewed by other researchers. The research was conducted based on the analysis of data from more than 7,000 Einstein healthcare workers infected with SARS-CoV-2 between 2020 and 2022. Of this total, 1,933 (27.4%) experienced covid a long-term versus 5,118 (72.6%) who did not develop the condition.

According to Vanderson Sampaio, a researcher at ITpS and one of the authors of the article, the definition of long-term covid used in the study was that of the US Center for Disease Control (CDC): “They are people with previous coronavirus infection who continue to have persistent symptoms of the disease for more than four weeks. Symptoms include fever, nasal congestion, tiredness, fatigue, headache, cough, difficulty breathing, among others,” he explains.

More than half (51.4%) of study participants who experienced long-term covid had three or more persistent symptoms. Another 33.3% had only one symptom and 14.9% had two. The most common symptoms were headache (53.4%), muscle or joint pain (46.6%) and nasal congestion (45.1%).

According to ITpS, the study showed that reinfection increased the chance of persistent symptoms by 27%. Among those who had two or more infections, the rate was 38.9%.

“This was the most striking result because it shows that people cannot think that, if they have caught the virus once, they already have immunity and are free to abandon protective measures. Re-infection with the virus increases the inflammatory reactions of the body , the risk of a severe case increases and, consequently, of the long covid,” says Sampaio.

The fourth dose is essential

The same mechanism underlies another study finding: that only the four-dose vaccination schedule was able to protect against lingering symptoms. The research points out that the fourth dose reduced the chances of long covid by 95% compared to the unvaccinated group.

According to study data, among participants who did not receive any vaccine dose prior to infection, the long-term covid onset rate was 36.7%. Among those who took the two regular doses, the rate dropped to 29%. In the group that had already taken three doses it was 15.5%, and in the group with the full four-dose vaccination schedule, only 1.5% developed persistent symptoms.

According to the ITpS researcher, the numbers show that protection against severe cases and long-term covid increases with each dose taken, but he points out that the fourth application is crucial to ensure protection against worsening of the disease and against prolonged conditions. He says studies are not yet conclusive on the extent of the protection given by the third dose against long covid and, therefore, the main recommendation now is to look for the full scheme.

“People with the full vaccination schedule develop more antibodies, have a better immune response to the infection, which protects them from developing severe forms. According to data from the press media consortium, less than 20% of the Brazilian population has already taken the fourth dose.

Higher prevalence among women

In the study, long-term covid was more prevalent among women, a result already observed in other studies. According to ITpS, women are 21% more likely to contract Covid-19 in the long term than men.

A similar study conducted by the institute in collaboration with the USP School of Medicine (FMUSP) showed a similar pattern. In the survey, conducted with 1,540 healthcare workers at the Hospital das Clínicas by FMUSP infected with the coronavirus, the long-term risk of covid was doubled among women.

While this has already been proven in more than one study, the science is still unclear as to why. According to the researchers, further studies are needed to evaluate whether this finding is related to biological/genetic or behavioral factors.

“We know women take better care of their health, so does this result have to do with them reporting more long-term covid symptoms? We don’t know yet, this needs to be studied,” Sampaio says.

Variants

The study by ITpS and Einstein also demonstrated that the long-term incidence rate of covid was lower among those infected with the more recent variants, such as Delta and Ômicron, compared to individuals contaminated by the original Wuhan strain and its derivatives and by Gamma, which originated in Manaus and caused the second and deadliest wave of the pandemic in the country, in the first half of 2021.

According to the researchers, in addition to the lower lethality of the most recent strains, the main factor explaining the lower long-term incidence of covid among the recently infected is vaccination. In 2020 and the first half of 2021, the vaccine was either still in development or limited to a small group of people and in the primary vaccination schedule (no boosters).

Sampaio warns, however, that the fact that the most recent variants represent a lower long-term risk of covid so far does not mean that the next ones will behave the same way. “This is absolutely not true. We need to look at the new subvariants and assess whether the scenario (less serious and fewer cases of long covid) remains. Today we have the XBB.1.5 Ômicron subvariant already prevalent in the United States and seen with concern for its transmission capacity”, warns the researcher.

Also remember that, in addition to the individual risks of reinfection, the unbridled spread of the virus increases the risk of genetic mutations and the emergence of variants that can escape natural immunity and the antibodies conferred by the vaccine. “Look at what’s happening in China today (with an increase in cases after the withdrawal of the zero covid policy). It’s an island of viral gene mutations. From there, new variants will probably come out and spread around the world and we have to prepare for what is to come,” he says.

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Source: Terra

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