‘Third dose against Covid in the elderly is due yesterday,’ says Fiocruz doctor


Although the advance of vaccination against Covid in the country brings signs of hope, the still low vaccination coverage (with two doses) and the circulation of the more contagious delta variant of the coronavirus draw the attention of specialists, who already see worrying signs in the rate of occupation of ICUs and in the hospitalized age group.

For Julio Croda, 43, infectologist and researcher at Fiocruz, the increase in hospitalizations of people over 80 years old makes it imperative to apply a booster dose in this population, the first that was vaccinated in the country, together with health professionals.

Last Thursday (19), the Minister of Health, Marcelo Queiroga, said that the application of a third dose of the vaccine will only occur after the entire adult population has received two doses of the vaccine.

Photo: Geraldo Bubniak/AEN

The minister’s speech, however, is in line with what has been done in several countries.
Croda defends that the booster dose for the elderly is given at the same time that vaccination in other age groups is still ongoing.

In an interview with Folha de S.Paulo newspaper, he also spoke about how to guarantee the second dose to the more than 7 million Brazilians who did not complete their vaccination schedule and the game changer caused by the delta variant.


Question – Should the Ministry of Health today prioritize the application of a second dose in adults or start to apply a third dose in the elderly and immunosuppressed?

Julio Croda – Brazil as a whole has a very uneven pace of vaccination; there are states that have already advanced a lot from the point of view of applying the first dose [D1], and the vast majority of states have already applied the second dose at least to the elderly over 60 years of age. But the ideal would be to guarantee the second dose for all people over 50 years old before starting to advance in the younger ones, before anticipating the second dose in the younger ones. It is important to understand why 7 million people have not yet taken the second dose, especially the elderly, and seek these people before moving on to teenagers, for example.

Q. – Although in Brazil we have 91% vaccination coverage for seniors over 65 years of age, how can these people seek the second dose?

JC – In terms of coverage, 91% is very good, but the ideal is to reach above 95%, especially in this group. In this sense, what must be done is at the municipal level, together with the primary care teams, to seek out people who received D1, but not D2. [segunda dose], go from house to house looking for these individuals to apply the second dose.

Q. – A study coordinated by you found Coronavac to be less effective in older people, with protection against Covid ranging from 28% to 62%. Does the fact that most elderly people over 65 in Brazil have received two doses of Coronavac at the beginning of the year worry you?

JC – The question of age is for yesterday, because we are already seeing an increase in hospitalizations in some states, such as São Paulo and Rio de Janeiro, with the arrival of the delta, especially in this age group. If there is now the circulation of a more transmissible variant and the impact on this age group is already being observed, with vaccines with lesser effectiveness, this is an indication of the need to implement a booster as soon as possible.

What we do not have yet are data regarding the increase in hospitalized immunosuppressed people, so perhaps the states that have already advanced in the vaccination of adults over 18 years old, have already applied D1 in everyone over 18 years old, could indeed start a booster scheme in older, starting with people who completed their vaccination schedule more than six months ago, with no impact on the vaccination campaign for young people and adolescents.

Q. – In the case of immunosuppressed people, the US government approved the application of a third dose not as a booster, but as a normal vaccination schedule.

JÇ – It is important to differentiate between this: a 3rd dose of the vaccine schedule, which would be for the immunosuppressed, and a booster dose for the entire population, starting with the oldest, six months after the application of the second dose. As in Brazil the vaccination campaign started in January, we already have some people, mainly those over 90, 80 years old, who have already spent six months since the second dose, and it could start there.

The biological mechanism is the same, there is a decrease in the immune response in relation to the usual vaccine schedule, both in immunosuppressed and in the elderly. The drop is so much in neutralizing antibodies [capazes de bloquear a entrada do vírus nas células] how much effectiveness, showing this decrease in protection. It does not necessarily mean lower protection for severe forms, but this is an indication that makes one think that, over time, with this drop in effectiveness, a booster dose is needed.

Q. – What would be the main difficulty in starting the application of the 3rd dose without first completing the 2nd in the adult population?

JÇ – The impact on the PNI would be minimal, because there are only 4 million people over 80 years old and immunosuppressed, with an even smaller number of health professionals over 60 years old. The difficulty from a practical point of view, in the case of immunosuppressed people, is the Ministry of Health’s determination of who these people are, what conditions would be included in the classification of immunosuppressed.

Q. – The so-called vaccine escape cases seem to be more recurrent in older people, so there aren’t so many cases in younger individuals and, when there are, they are generally milder?

JC – For sure. There is a survey that clearly shows that in individuals with two doses of the vaccine who ended up in hospital and eventually died, 96% were people over 60 years of age.

Q. – ​And in relation to the vaccination of adolescents, is it too early to think about immunizing this group?

JC – The vaccination of teenagers is mainly focused on reducing transmission and the risk of infection for technicians, for teachers, for school employees to be safe when returning in person. It is important to understand that the context of some states, such as RJ and SP, is one of delta acceleration, with an increase in hospitalizations and deaths in a public that is not children and adolescents, and even so we have a number of states that have started vaccination in this group and do not assess the reinforcement in the elderly.

Understanding the context of the country as a whole, that we can advance in the immunization of adolescents while we cannot leave out the third dose in the elderly, is essential, and it is up to each manager to optimize the doses they receive and assess which best strategy. What makes no sense is to privilege adolescents, because in practice we are seeing an increase in hospitalizations among people over 60 years of age.

Q. – With the vaccination of older age groups close to being completed, or at least largely complete for those over 60, is the tendency for the disease to get younger and younger?

JC – That was an idea in the beginning, but the delta messed everything up by being more transmissible and with a little more escape of the immune response. As we advance in vaccination for younger age groups, the tendency is for it to focus on the elderly, associated with a natural drop in antibodies that occurs over the months. So, if you combine these three factors in elderly people, who are already at higher risk of hospitalization and death, who already have a lower immune response to vaccines, and delta is even more complicating, this can lead to a substantial increase in the number of cases, and above all hospitalizations. And there are clear data demonstrating this: between June 6th and 12th, in the 23rd epidemiological week, the elderly represented 27% of hospitalized patients and now, between August 1st and 14th, that is, two months later, this is equivalent to 44% .

Q. – And as for health professionals, does a booster dose in this group make sense?

JC – It is important to understand that at this time, it is necessary to have more doses of vaccine in order to advance. The request for a booster dose in health professionals is adequate, other countries are already adopting this, but it is necessary to stratify the risk, a health professional over 60 years old has a higher risk than one over 30. Personally, I don’t see it no problem in revaccinating health professionals over 60 years after booster injection in the elderly and immunosuppressed.

Q. – Despite the advance of vaccination, is it prudent now to think about resuming services and meetings, including sporting events with fans and wedding parties?

JC – It’s too early, because our vaccination coverage, especially in the full regimen, is still very low. Compared to the United Kingdom, for example, which has a higher second dose coverage for the general population, there was a significant increase in new cases in that country, that is, the vaccine was not enough to control infections. But there was no proportional increase in hospitalizations and deaths, which shows that vaccines continue to work for more severe cases of the disease.

The problem is when the flexibilization is based on an account of people with D1, which in the context of delta changes totally. Much greater coverage of D2 is needed, especially in the most vulnerable groups, as this alone will guarantee protection for the severe forms of the disease.

Q. – ‘Mr. it was part of the SP government’s Coronavirus Contingency Center, which was reduced last week by the governor. Did this occur in part from views against reopening? Are you part of the new, leaner scientific committee?

JC – I’m not still on the committee. The decision of dissolution was made by the governor to reduce the number of people who advised because he believed that the pandemic had diminished. I am independent in everything I say and think, the committee has always been independent in its positions, and I hope it will continue. I believe that the decision of total flexibility was premature, this was a discussion we had in the committee, we wanted another indicator, such as vaccination coverage with two more advanced doses to start this type of flexibility, and not just advance in D1.

Q. – Will the coronavirus become endemic?

JC – Yes, and the delta variant came to demonstrate that. All available vaccines, and it is important to make this clear, continue with high protection against hospitalization and death, but the loss of effectiveness against the moderate forms causes the virus to continue circulating and, by continuing its transmission, more mutations will occur and new ones variants may arise. What should happen over time is that, with the vaccination and vaccination booster, we will be able to prevent the progression to serious illness, but not the circulation of the virus.

It was like that in the H1N1 epidemic. This acquired immunity is not capable of preventing the circulation of the virus, it cannot control the emergence of new variants, but it controls the risk of progression to a serious condition associated with the need for hospitalization very well. Sars-CoV-2 is still very recent in the population, having adapted to humans less than two years ago. It is natural that it becomes endemic and eventually, from time to time, other major epidemics associated with new variants should occur.




Born in Salvador (BA), he graduated in medicine at the Federal University of Bahia, with residency in infectious and parasitic diseases at Hospital das Clínicas at USP and a doctorate in infectology at the same institution, with a sandwich period at the Pasteur Institute, in France . He is 43 years old, is a researcher at the Oswaldo Cruz Foundation (Fiocruz) and a professor at the Federal University of Mato Grosso do Sul. He was director of the department of immunizations and communicable diseases of the Health Surveillance Secretariat of the Ministry of Health from 2019 to 2020.