Since January 13, the booster against covid is recommended for the general adult population in Spain. 78.8% of those over 50 and 88.9% of those over 60 have already had it, said yesterday the Minister of Health. If those who are missing have doubts, here we try to solve them.
The data confirm that it is the vaccines, in their full guideline, which are containing the onslaught of the sixth wave in hospitals: “A person between 60 and 79 years vaccinated is 16 times less likely to be hospitalized, 29 times less likely to go to an ICU and 20 times less likely to die,” said yesterday the Minister of Health at a press conference.
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But it is also noted a loss of protection of vaccines against mild disease and infection after a while.
Several studies, including the ENE-COVID Senior, whose results were presented yesterday by Sanidad, show that the booster dose restores defenses and places the vaccinated person “in a zone of immunological safety”, said the director of the Carlos III Health Institute (ISCIII), Cristóbal Belda. “A third vaccine dose in patients over 65 years of age – the population studied in ENE-COVID Senior – increases the overall titers of antibodies against the receptor binding domain (RBD) by more than 20 times”.
According to the reports provided by the Scientific News and Information Service, we can know the answers to the most frequently asked questions about the current situation of the vaccines, the boosters and how it affects the population. All of them are of great general interest and are specified below.
Are booster and booster doses the same thing?
No. As clarified in this Ministry of Health guide, the additional dose is a third dose necessary for people with weakened immune systems. For them, the full (or primovaccination) regimen consists of three doses.
The booster dose is the one given to people with normal immune systems after they have received their full or primary vaccination.
If I don’t get the booster, do I lose protection?
Yes, especially now that the dominant variant in Spain is omicron. All the studies find that the effectiveness of the vaccine “declines as time elapses since the last dose and improves after a booster dose”, as stated in the latest Health report on the subject (December 18), and the phenomenon is more pronounced with Omicron. “The effectiveness against symptomatic infection [by Omicron] estimated in a UK study was between 0% and 19% after two doses, and between 54% and 77% after a booster dose,” the report states. Protection against hospitalization, however, “remains high.
The risk of infection while vaccinated and of reinfection (after the disease has passed) is also higher with omicron. A study by the British Imperial College has estimated a 5.4 times higher risk of reinfection for omicron than for delta in England.
If the full regimen protects against severe disease, why do I need a booster dose?
Protection against severe disease is maintained with the full vaccination schedule thanks to cellular immunity, which is responsible for “storing memory of past attacks,” says Carmen Martín, an immunologist at the Hemotherapy and Hemodonation Center of Castilla y León. But the antibodies block the key with which the virus enters the cells, thus preventing infection.
The booster dose, by recovering circulating antibodies, strengthens the defensive barrier against infection and also, therefore, contributes to curbing community transmission. For this reason, “due to the current epidemiological context and the expansion of the omicron variant, it is recommended to continue increasing the vaccination coverage percentages and the administration of booster doses in target populations”, states the Health report.
Is it recommended for the entire population?
On October 5, 2021, the Public Health Commission approved the recommendation to administer a booster dose to people over 70 years of age. In the following months, the recommendation has been extended to various groups, until last January 13 it was extended to all those over 18 years of age “in an orderly manner by age cohorts and prioritizing people with risk conditions and those who have received the first vaccination for the longest time,” the vaccination strategy page states.
Is it also for pregnant women?
Yes. The Federation of Spanish Scientific Medical Associations (FACME), among which is the Spanish Society of Gynecology and Obstetrics (SEGO), has updated its recommendations on the anticovid vaccine in pregnant women and points out that “there is no data to suggest that the risk of the third dose is different from that of the previous doses, neither for the mother nor for the fetus”.
Is the booster dose recommended for children?
The director of EMA’s Vaccine Strategy, Marco Cavaleri, said at a press conference a week ago that there is still insufficient data to recommend a third dose in children under 12 years of age. Also, in a recent meeting with the media, representatives of the World Health Organization (WHO) have denied that for now there is evidence that a third dose is necessary in that age group.
When do I get it?
The dates for administering the third dose vary according to certain circumstances. In general, five months should have passed since the second dose if the first vaccination was with an mRNA vaccine (Pfizer or Moderna), and three months if one dose of Janssen or two doses of Vaxzevria (AstraZeneca) were received. But there are exceptions (see questions below).
What if I was infected before the first vaccine or between doses?
In both cases, the recall will be after five months of the complete regimen if the last dose was with Pfizer or Moderna, or after three months if it was with AstraZeneca or Janssen vaccine, specifies Health.
What happens if I am infected after having the complete regimen?
You have to wait five months from the last dose received if it was with an mRNA vaccine, and three months if it was with a Vaxzevria or Janssen vaccine. In addition, the following conditions must be met: the disease must have been completely overcome; the isolation period must have ended; and four weeks must have passed since the diagnosis of infection.
These guidelines are valid regardless of the primary vaccination schedule received (2 doses of Vaxzevria, 2 doses of mRNA vaccines, 1 dose of Janssen, 1 dose of Vaxzevria+1 dose of mRNA vaccine, history of covid-19 + 1 dose of any vaccine).
If only four weeks elapse between infection and booster -contagion after complete regimen-, is there any risk?
No, as several immunologists have explained to the Covid Vaccine Media Hub: “It will not be harmful,” says Ignacio J. Molina, Professor of Immunology at the University of Granada. “Immunization has been brought forward since a delta-infected person can easily become infected with omicron. The period would influence the level of efficacy of the response and protection against the new variant, but in no case would it represent a higher risk of adverse effects”.
Salvador Iborra, Immunologist at the Complutense University of Madrid, is of the same opinion: “Accelerating the third dose would not be harmful for those people who, having received the full regimen, have been infected with the virus”.
What happens if the third dose is received while unknowingly infected?
If you have symptoms compatible with covid-19, the recommendation is to check that you are not infected before receiving any dose of the vaccine.
But, what if you have received the vaccine when you were positive without knowing it, because you did not have any symptoms and they have appeared just after? Marcos López Hoyos, president of the Spanish Society of Immunology, clarifies to SINC that “nothing happens”. It is a situation that has probably occurred many times without the vaccinated person being aware of it.
Why can the third dose be of a different vaccine (heterologous pattern)?
Studies indicate that heterologous vaccination gives better results. Last December, the Spanish Medicines Agency echoed the recommendations of other evaluating bodies and stated: “Evidence suggests that the combination of viral vector-based vaccines and mRNA vaccines produces good levels of antibodies against covid-19 virus (SARS-CoV-2) and a greater T-cell response than when the same vaccine is used, either in primary or booster vaccination”. Heterologous regimens are generally well tolerated.
Will there be a fourth dose?
The future strategy for further curbing the pandemic has not yet been mapped out, EMA Vaccine Strategy Director Marco Cavaleri recently commented. The EMA does not believe that giving booster doses every few months is “sustainable in the long term (…). We cannot continue to give booster doses every three or four months [to the general population].”
The vulnerable population will receive more doses. On January 13, Health announced that “those who received additional doses of mRNA vaccine because they are considered to be at higher risk” -group 7 of the vaccination strategy- or are being treated with immunosuppressive drugs -update 9 of the strategy- will receive a fourth dose five months after the last dose.