Advances with vaccination with doses from different laboratories / AP

The possibility of combining vaccines that was opened this week not only cleared a horizon for those who wait for the second dose of Sputnik V but, in tune with a changing reality and that sometimes seems to be “trial and error”, generated some doubts about what is the most convenient when inoculating. Should I apply the second dose of another vaccine or wait? Is it safe and effective to combine vaccines? Can I choose which one to give myself? These are some of the many concerns of many people who want to protect themselves from the virus but, given so much information around, they do not know what is the best way to do it.

In principle, and in the face of what would appear to be an imminent third wave due to the circulation of the Delta variant, specialists agree on the importance of completing the immunization schedules against the coronavirus “as soon as possible” using the combinations that proved to be safe and effective.

The chose

As is known, last Wednesday the Ministry of Health announced that, as a result of international and national scientific evidence, people will be able to choose between waiting for the second dose of the vaccine that has already been applied or combining schemes as follows: first dose of Sputnik V with AstraZeneca or Moderna and first dose of AstraZeneca with Moderna. In the recommendation, the health portfolio indicated that these heterologous schemes will be offered in the event that “the vaccine used as the first dose was not available, or if the person had anaphylaxis or a severe allergic reaction to the first dose.”

It is estimated that in Argentina there are 1,300,000 people who took the first dose of Sputnik V more than three months ago and, although the immunity granted “does not expire” -something that all experts emphasize-, completing the scheme reinforces protection and makes it more durable.

In recent days, many concerns have arisen, but undoubtedly the most common of all is, as said, whether or not to apply the second dose of another vaccine or to wait. “In any vaccination campaign, one of the most important premises is not to lose opportunities,” says Ricardo Rüttimann, pediatrician and infectologist and coordinator of the Vaccine Commission of the Argentine Society of Infectious Diseases (SADI) -. Therefore, if the person has the possibility to complete the vaccination schedule that began with Sputnik V with AstraZeneca or Moderna, they should do so as soon as possible ”.

For Rüttimann, “the success of a vaccination campaign depends largely on reaching the sooner the largest number of vaccinated people and the more complete the coverage, the better it will be for the entire population as a whole.”

Regarding whether it is safe to give two different vaccines or whether this strategy reduces efficacy, the infectologist Elena Obieta remarks that “all the studies that have been carried out with a combination of vaccines, both in the world and in Argentina, have shown that they are safe and effective; This means that they did not generate adverse effects as long as the response of the immune system was similar or superior to the homologous regimens (two identical vaccines). In the case of the combination between Sputnik V with Sinopharm, we still have to wait for the results ”.

One of the points that specialists highlight the most is the importance of completing the vaccination schedule as soon as possible. Regarding this, the clinical doctor Mariana Lestelle points out that “the first vaccines to prevent Covid-19 had emergency approval at the end of December 2020, with the campaign beginning in our country that same month, when the predominant variant of SARS-CoV -2 was the original. Because it was a commodity that the world demanded, vaccine production did not keep pace with the need for vaccination. That is why in this first stage, the watchword in the world (not only in our country) was to vaccinate as many people as possible with a single dose, extending the interdose intervals ”.


Lestelle described that “eight months later, with the appearance of new variants of the virus, and in particular with the Delta variant, which is the one that has generated new outbreaks in the world and is much more contagious than the original, the current need is to complete vaccination schedules, that is, having both doses of vaccines. So, given the possibility of having a second dose, even if it is different from the first inoculated dose, there is no need to wait. It is necessary to complete schemes to strengthen the immunity given by the first dose ”.

Regarding whether one can choose between AstraZeneca or Moderna as a second dose, another of the frequently asked questions by people, experts say no. In any case, what can be chosen is whether to wait for the availability of component 2 of the Sputnik V vaccine or to accept a combination. If the combination is accepted, until now, the second dose that will be offered will be that of AstraZeneca or Moderna according to the availability of each jurisdiction.

“It is vital to complete schedules to strengthen the immunity given by the first dose”

Another important aspect to take into account is that it is not necessary to call anywhere or manage a new shift, since those responsible for the vaccination plan of each province will contact each other to give the options. The different jurisdictions are calling, in general, first to those who are at risk population (elderly people and then with comorbidities) in order according to the time that has elapsed since the first dose of Sputnik V.

Many people who got the Russian vaccine and are waiting for their second dose wonder when it will be their turn if they decide to wait. For all of them, the experts’ answer is simple: when available.

Last Tuesday, it is good to remember, the Gamaleya Center reported that it approved the samples of the second component that had been produced in Argentina by Richmond Laboratories, for which 150 thousand doses that were already ready were released for application. As planned, Richmond will be able to produce more than 3 million doses of the second component of the Sputnik V vaccine in August.

In addition, the producers of Sputnik V announced last Wednesday that during August “all temporary delays in the delivery of the second component of the vaccine will be completely resolved.” This is because Sputnik V “has established production agreements with manufacturers in 14 countries and will double its capacity in September thanks to the association with large firms such as the Serum Institute of India.”

Another question some ask is whether there is a history of heterologous (combined) schemes for other diseases. On this question, Obieta details that “an example of a heterologous scheme to complete vaccines is what we do against pneumococcus; first the one with 13 serotypes is given and then the conjugate of 23 serotypes is given ”. In addition, he recalled that “Sputnik V is itself a heterologous scheme because it has two different components in the first and second doses. We also get vaccinated every year against the flu based on the viruses that are circulating and because the antibodies fall, and surely they are made with different brands of vaccines, so the combined schemes already have a lot of history in terms of safety ”.


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