After more than a month of falling cases globally, new infections of COVID-19 began to increase around the world In the past week. With strong lockdowns in Asia and exponential increases in Europe, for the World Health Organization (WHO) the cause is “A combination of factors, including the highly transmissible Omicron variant and the BA.2 subvariant, added to the lifting of public health and social measures.”

In this context, and with a view to the start of the winter season in the southern hemisphere, the pharmaceutical companies Pfizer/Biontech and Moderna have already requested the US FDA to authorize the emergency use of a fourth dose of their mRNA vaccine against COVID -19 (second reinforcement or recall), in the face of a possible increase in cases and “the possibility of another wave of the pandemic.”

In some countries, such as the case of Spain, the application of a fourth dose of the vaccine against COVID-19 was approved but exclusively for immunosuppressed people and five months after receiving the last dose.

The debate was immediate, especially considering what is happening in Argentina where many people are still missing without taking the third dose. According to the Public Vaccination Monitor, they are 15,493,064 people who have the booster dose in Argentina.

The prominent infectologist Hugo Pizzi (MN 54,101) considered that the implementation of a fourth dose must be imminent. “There are several countries that are applying the fourth dose and there are two things to keep in mind: we are in a transition period, where it is appropriate to continue with the care and we are going to enter a climate that is not favorable for respiratory diseases”, he explained.

In Argentina, “the only people who would receive a fourth dose are those who, by indication, received an additional dose in November or December”as he had specified last week to Infobae the undersecretary of Health Strategies of the Ministry of Health of the Nation and responsible for the vaccination plan, Juan Manuel Castelli.

These are immunocompromised people, either due to illness or who are undergoing immunosuppressive treatment. In addition, after four months of the additional dose, people 50 years of age or older who had received a primary schedule of inactivated virus vaccine, such as the one developed by Sinopharm, will also receive a fourth dose in the country.

In addition, Last week, the national health portfolio enabled the fourth dose of the vaccines against COVID-19 for people who have received Sputnik V, and must travel to countries that do not accept itwho may apply any of the inoculants authorized by the WHO.

Now, on the suitability or not of extending this second booster dose to the entire population, from the Spanish Association of Vaccinology its co-founder, pediatrician, and vaccine expert, Dr. José Antonio Navarro Alonso, sees it as “difficult” to respond to this He asks because, as he assured, “everything will depend on epidemiological and virological surveillance in the coming weeks.”

As he considered in an interview with infohealth, “From the point of view of the antibodies, it seems that their peak after the fourth dose is similar to that reached after the third, which indicates that the maximum immunogenicity would be reached after the third dose”.

Along the same lines, the president of the Spanish Society of Immunology (SEI), Marcos López, shared the need for the administration of a fourth dose against COVID-19, “only in very vulnerable subjects”, and was in favor of using preferably other types of vaccines if they are available, that is, in this case use others that are not based on the SARS-CoV-2 protein S, on which the current vaccines are based, and use others that affect other parts of the aforementioned coronavirus.

“It is true that in some very vulnerable subjects a fourth dose may be useful, but we also have therapeutic tools such as antivirals or monoclonal antibodies”he highlighted.

consulted by Infobae, the infectologist doctor Eduardo López (MN 37586), to begin with, clarified that “the only data on the fourth dose that are available correspond to the studies carried out by Israel with the Pfizer mRNA vaccine.” “In that country it was seen that it was useful to give a second booster dose (that is, four in total) because it made them drop the number of cases,” said the specialist, for whom “Compared to the Omicron variant, three doses are inexorably required, so discussing the need for a fourth when in Argentina a large percentage of the population has not yet received the third is complex.”

It is that according to the latest data available in the Public Vaccination Monitor, the online registry of the Ministry of Health that shows in real time the immunization operation throughout the Argentine territory, of the 36,838,041 people who completed their initial two-dose scheme (it should be noted that there are still 3,730,045 who did not receive the second dose) 18,520,752 received their third, and almost as many (18,317,289) received their second dose more than five months ago and still no reinforcement.

“The fourth dose is a reinforcement of the third, and what was seen in Israel is that the amount of antibodies does not go up much more, but the effectiveness of the vaccine does increase and people get sick less”highlighted López, who pointed out that “some countries are giving a fourth dose in certain populations, such as immunosuppressed people, people over 70 years of age and health personnel.”

Along the same lines, the infectious disease doctor and member of the Vaccine Commission of the Argentine Society of Infectious Diseases (Sadi) Francisco Nacinovich (75,823), contributed that “the application of a fourth dose is still a matter of debate.” “I think some populations would benefit, and in addition to the immunocompromised and those over 50 years of age who received their initial regimens with Sinopharm, it seems to me that, based on the time they have taken the third dose, if they have had COVID or No, a group that I would consider to give a fourth dose is those over 60 years of age and health personnel”considered the specialist to this medium, who emphasized that “he would not apply it in a generalized way to everyone”.

In the opinion of the professor of Immunology, Africa González, and former president of the Spanish Society of Immunology, “a second booster dose could be indicated for some elderly people, who live in residences, or are immunocompromised.” “For now it is too early to say, if, as has been seen, the vaccine does not prevent contagion, it would not make sense to give it to the general population because even people with three doses have been infected, and in this sense Israel was also what he commented. : it makes no sense to give it to all people”added the expert.

For the epidemiologist Elena Vanessa Martínez, president of the Spanish Society of Epidemiology (SEE), the need to apply a second booster dose could be indicated in vulnerable people. “It would be something to think about but always based on the fact that it is shown that these people become more infected because the protection of the vaccine has decreased over time. If it doesn’t go down over time It would be necessary, but the experts should analyze it,” he insisted.

The Spanish professor of Immunology Alfredo Corell went further, and stated that, in his opinion, “The third dose of the vaccine against COVID-19 would not have been necessary in a massive way, and it was only necessary for those people with low defenses due to different treatments”. “And therefore with less reason the fourth is necessary,” she remarked.

In that sense, his recommendation about extending it to the general population is that before putting it on, “at least the level of antibodies in the blood” is measured in each person, and if they have enough, they are exempt from this fourth dose because, according to what he considered, “ a repeated injection of the same product in such a short time can in the long run be harmful and not beneficial”.

Returning to the case of Israel, according to López, “what was seen is that if three doses are given, the mild forms of the disease are probably not avoided, but hospitalization is, while with a fourth dose, even mild cases are prevented.”

“The problem we have with all the available vaccines is that we still need to know how long the immunity lasts,” said the infectologist. In general, it is considered to last from six to eight months, although some authors consider that cellular immunity is greater and lasts at least a year”.

For him, in Argentina “that almost 50% that lacks the third dose should be prioritized”, since “although infections are going down, it is possible that a regrowth will appear in the face of winter”.

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