Almost half of adults vaccinated against Covid are delayed 3rd dose

Almost half of Brazilians able to take the third dose of the Covid-19 vaccine have not yet received the booster. There are approximately 56.6 million people who are late or have ignored the need for the additional dose.

Experts view the low coverage with concern, especially after the release of the use of masks in several states and municipalities.

According to survey of sheet with data from the Ministry of Health, about 122.8 million adults are eligible to receive the booster because they were vaccinated with the second dose four months ago or more. However, 46% of them have not yet updated their immunization.

The country has not been able to advance in the application of the additional dose. Last Tuesday (22), about 41% of the population aged 18 and over had all three doses, a number not much higher than a month ago, when coverage reached 38%.

The low proportion is worrisome, especially with the circulation of the new omicron subvariant. According to studies, BA.2 can be up to 40% more transmissible than the predecessor lineage.

As with the previous strain that was circulating in the country, research indicates that BA.2 may have immune escape. Therefore, those who have taken at least three doses of the vaccine have greater protection.

“It is very important that the country manages to advance in the coverage of the third dose in view of the scenario that is forming. It seems that we are ending the cycle of the BA.1 omicron, but we are already seeing the advance of BA.2 cases in Europe , mainly in countries that have a low proportion of vaccinated with the booster”, says infectious disease specialist Raquel Stucchi, professor at the Unicamp School of Medicine (Universidade Estadual de Campinas).

The lifting of sheet shows that coverage with three doses is higher in the older eligible population since the end of September 2021. But almost a third of people aged 60 and over have not yet received the booster.

In this group, 1 in 4 eligible to receive the third dose did not return to update protection — about 7.5 million people.

By mid-November 2021, about 30 million Brazilians in this age group (92%) had been vaccinated with two doses. That would be, therefore, the approximate number of qualified to have the reinforcement in the arm four months later, at the beginning of this week.

Coverage with the third dose gradually decreases in younger age groups. Among adults aged 40 to 59, it is 45%. Just over half of those qualified returned to update their immunization.

Among those aged between 18 and 39, only 39% of those eligible had already sought reinforcement. This range concentrates the largest number of Brazilians with a potentially delayed third dose: around 29 million people.

Despite the lower ceiling, as it was included later in the campaign, this range could already have almost two thirds of coverage (65%), considering the total of vaccinated with two doses four months or more. Until Tuesday, however, only a quarter of Brazilians aged between 18 and 39 had received the reinforcement.

Overall, across the entire population aged 18 and over, booster coverage was 41%. The expectation, however, is that up to 76% were fully immunized.

Since November, the administration of the additional dose is recommended for all adults.

As applications have advanced little in recent weeks, experts fear that immunization in the country has stagnated. Therefore, they emphasize the importance of new actions by health authorities.

“The studies we have today already show that the third dose is part of the primary vaccination schedule, it is no longer a cycle of two doses. The population needs to be informed and aware that, without the third dose, it is not safe”, he says. epidemiologist Ana Maria Brito, from Fiocruz.

She explains that the new variants have caused cases of reinfection in other countries with low vaccination coverage. This is the situation in the United Kingdom, which is experiencing an explosion of contaminated with the new subvariant and has about 50% of the population with the three doses.

Specialists consulted by the report consider that a safe level would be to have at least 90% of the population with the booster dose.

For them, governors and mayors should have waited for the index to be higher before releasing the use of a mask in closed environments. In most states, the representatives justified the flexibility with the argument of having a high rate of vaccinated with the first dose.

“Decisions should be made based on the third dose information, which is when people are most protected. The moment is of uncertainty with the arrival of BA.2 and, in a situation of uncertainty, the best would be to adopt the principle of precaution”, says epidemiologist Roberto Medronho, professor at UFRJ (Federal University of Rio de Janeiro).

Another factor of concern pointed out by experts is the arrival of autumn in the country, when there is usually an increase in respiratory diseases.

“Colder days can cause a dangerous mix, even more so after the flexibility of wearing a mask in several places. There is concern about the respiratory diseases of the time, Covid and even the possibility of developing both at the same time, as happened at the beginning of the year”, recalls Stucchi.

Between December and January, the country had an explosion of influenza cases along with the wave of the ômicron variant, and there was a record of co-infection by the two, a phenomenon that was called “flurona”.

In Brito’s assessment, the stagnation of vaccine coverage of the third dose may contribute to a worsening of the country’s situation, since people without adequate immunization contribute to the greater circulation of the virus.

“People need to understand that the vaccine is not just protection for them, but for everyone. Without increasing coverage, we can have a worsening and have to go back on the flexibilities already made, which no one wants”, says the epidemiologist.