Vaccination against Covid-19 is only just beginning, but the evidence already shows that immunizing agents may represent the end of the pandemic. Studies published in the last few weeks show that people who received a vaccine and become infected with the Sars-Cov-2 coronavirus may have a reduced viral load, which should lead to a lower chance of transmission of the pathogen.
A study published on Monday (29) in the scientific journal Nature Medicine indicates that the vaccine BNT162b2, developed by the American pharmaceutical Pfizer and the German biotechnology company BioNTech is one of those that plays this role.
According to the article, people who received the immunizer and became infected with the coronavirus between 12 and 37 days after the first injection had a substantially lower viral load. “This reduced viral load indicates potentially less infectivity, contributing to the vaccine’s effect on the spread of the virus,” write the authors, scientists from Israeli research institutions.
Following the same line, the European Center for Disease Prevention and Control (ECDC) published a technical report on Monday (29) based on studies that point out the benefits of vaccination to contain the spread of the virus.
According to ECDC, vaccinating a household member could reduce by at least 30% the risk of other people living in the same location becoming infected with the coronavirus.
“There is evidence that vaccination significantly reduces viral load and symptomatic and asymptomatic infections in vaccinated people, which can translate into decreased transmission, although vaccine efficacy varies according to the immunizer used and the target population” says the ECDC note.
Preliminary data indicate that the Covishield vaccine, developed by the pharmaceutical company AstraZeneca and the University of Oxford, is capable of blocking the transmission of the virus by about 70%. Data from an Israeli study indicate that the Pfizer / BioNTech vaccine has a similar capacity. There is still no data to guarantee that all vaccines against the disease have the same function.
The ECDC document also points out that a second infection with the coronavirus is a rare event. “Results of studies confirm that the protective effect of a previous infection with Sars-CoV-2 varies from 81% to 100% after the 14th day of infection onset, lasting for a period of five to seven months [até onde os estudos permitem verificar]. Protection for people over 65 years of age is lower ”, says the text.
However, the study published in Nature Medicine and the ECDC report warn that there is still no conclusive data on the same effect of vaccines on the transmission of the different variants that are emerging and worrying the medical and scientific communities.
“The different variants of the virus, which can be associated with different viral loads, must affect different parts of the population”, write the researchers from Israel.
The British (B.1.1.7), South African (B.1.351) and Brazilian (P.1) variants are the most worrisome at the moment and have already been registered in several countries around the world. Studies indicate that these new strains are more transmissible, but it is still unclear whether the Covid-19 they cause is more serious.
“As an RNA virus, Sars-CoV-2 will continue to evolve over time, and its potential to escape human immune defenses, induced by natural infection or vaccines, has already been documented,” says the ECDC report.
* With information from BHAZ
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