- Michelle Roberts
- Health Publisher, BBC News Online
Researchers say the vaccine reduces protection against Kovid-19 infections in people who receive two doses.
A study conducted in the UK using factual data examines the positive PCR results between May and July 2021 in more than one million people who received two doses of the Pfizer or AstraZeneca vaccine.
Pfizer increased protection from 88% in one month to 74% in five to six months after two doses. For estrogenica, it decreases from 77% to 67% in four to five months.
Especially to read on BBC Africa:
Although there are cases of infection in people who are fully immunized, vaccines still work well in protecting the population from the acute form of the disease and deaths from Kovid-19.
Vaccines can save lives
Public Health England, the UK government’s public health agency, estimates that the Kovid-19 vaccination campaign in England has so far prevented 84,600 deaths and 23 million infections.
Tim Specter, a professor at King’s College London (KCL) who led a data-based study from the epidemiological research app Joe Kovid, said the findings could fully explain some recently reported infections.
“The reduction in protection is predictable and is not a reason to avoid vaccinations,” he said.
“Vaccines still provide a high level of protection for most populations, especially against the Delta variant, so we still want as many people as possible with full immunity,” he said.
He predicts that protection against infection in the winter will drop to 50% and booster doses will be needed – but other experts are urged to be careful in predicting the coming months.
The UK is expected to begin offering a third booster dose of the Kovid vaccine to some next month, but the government is awaiting recommendations from an independent advisory body called the JCVI, which is reviewing evidence in support.
“Most people may not need it. Most people may have a natural increase because they already had a natural infection with covid, so they actually had three vaccines,” Specter said.
“So, if we are satisfied to give it to everyone (third dose) I think it should be handled much more carefully, it is a great waste and morally questionable depending on the resources we have. We need to pay more attention than last time,” he said.
Simon Clark, a specialist in cell microbiology at the University of Reading in the UK, explains that infection levels in a community can transcend an individual (virus) and change the likelihood of catching a covid, making it harder to obtain conclusions about immunodeficiency.
Alexander Edwards, also from the University of Reading, says it is important to understand when and to whom booster doses are needed.
“Vaccines cannot destroy humans or prevent all infections. Variants have a real and significant impact on public health, and many people in the UK are still dying tragically from this terrible virus.”
“The vaccines we have are very safe and effective, and even better than other vaccines that offer enormous benefits.”
“We need to plan our public health strategy in advance to take into account the potential for incomplete care and protection over time,” he said.
A similar study was released last week by the Office for National Statistics and the Oxford Vaccine Group.
Based on the PCR screening results of nearly 400,000 people infected with the Delta variant in the UK, it was found that the two-dose Pfizer vaccine was initially effective against 70% for the estrogen vaccine, and more than 90% initially against the symptomatic Kovid infection.
But over the course of three months, Pfizer’s defenses dropped significantly, while AstraZeneca’s immunity remained stable.
Professor Adam Finn, a government vaccine consultant, explained that other studies have shown that vaccines provide better protection against serious illness and hospitalization.
But he says: “We need to be very careful to see if this reduction (vaccination) begins to translate into more serious cases compared to minor diseases, as booster doses are required.”
At present, there is no definition of a booster vaccine in Brazil, but both the Ministry of Health and the Button Institute (responsible for finalizing coronavac production in the country) have agreed that they are evaluating and considering this possibility.