What experts say on cumulative vaccines in the face of the shortage of second doses against Covid

Of “the vaccination schedule will be completed” Yes “the doses do not expire”, the Minister of Health of the Nation passed this Wednesday to a new declaration concerning the plan against the coronavirus which seems to modify the two previous ones. “The possibility of the vaccine combination is being evaluated right from the start, ”said Carla Vizzotti.

The three sentences, at different times, fell within the framework of the same one-off and recurring journalistic question: how will the Government solve the problem? Difficulties accessing component 2 of Sputnik V. And also what will be the definition of the dilemma of continuing to give AstraZeneca as the first dose or if use it only to complete diagrams.

“Trading platforms can simplify vaccination and also the logistics of doses in vaccination centers. (…) If there is a technical consensus from other countries and, according to experience, we will talk about it with the different districts and we will see it, “continued the minister.

In the same conference, Vizzotti marked what is being done in the world. It should be remembered that Argentina does not do the same as its closest neighbors, such as Chile and Uruguay. In Argentina, they reign only Sputnik V and AstraZeneca. Also, to a lesser extent, Sinopharm.

“Countries recommended giving preferably the same mark, but the important thing is to finish with vaccination programs and several countries in Europe are exchanging vaccine platforms, ”he said.

But if you refer to Italy, for example, the association between AstraZeneca and Pfizer is not due to a lack of doses but to the death of an 18-year-old girl after being vaccinated with AstraZeneca, this which led to replace second doses of the formula developed in collaboration with the University of Oxford. The same thing happened in Chile, in the case of second doses of AstraZeneca in children under 45 years old.

Pfizer’s vaccines against Covid-19 they never came to our country and it’s being negotiated if they will at some point. So, can Sputnik V be combined with AstraZeneca?

Javier Farina, infectologist with the Argentinian Society of Infectology (SADI), stands firm on a statement: this should only be done what science says. And science, which still said little about the vaccine combination in general, said nothing about the mixture between the Russian vaccine and the Anglo-Swedish vaccine.

“Published testimonies (Editor’s note: in the sense of being made available in a prestigious scientific journal for peer review) there is, in some cases, only between Pfizer and AstraZeneca. There is no other combination reported, ”he said. Bugle.

But Farina opens the possibility that these combinations between the two predominant vaccines in our country will be studied. “This can be studied, since the Sputnik (itself) is a combination between two different vaccines, ”says Farina. Sputnik has two different components in each dose. Two adenoviruses. For this reason, technically they are two different vaccines.

“There would then be no risk in the combination (with another brand) but the real proof is that that the proof does not exist and it is a strategy which, in a context of global scarcity, must be studied and approached in order to assess the benefits. “

The AstraZeneca, on the contrary, you also need two doses but the first and second injection They are equal.

In Chile and Italy, it is already combined with Pfizer, remember, for safety in case of thrombotic effects in people under 45. In the UK, AstraZeneca is partnering with Pfizer, as well as Moderna, Novavax, Valneva, Janssen and Curevac, in a trial of some 3,000 people seeking to know which is best to use as a third dose compared to the new variants. Sputnik is not here.

The “possible” combination

Eduardo López, renowned infectologist and government adviser since the start of the pandemic, makes the same observation about the lack of studies supporting new combinations. But, based on her experience in testing the Chinese vaccine Cansino with Argentinian volunteers, she makes some combinatorial hypotheses. Always and “without a doubt”, it will first have to be verified by science.

“The first dose of Sputnik could be combined with Cansino’s vaccine. Cansino (which is a single dose but is being evaluated for a second as back-up) has the vector adenovirus 5, the same that Sputnik has in the second component (in the second injection), ”he says.

To check if the combination is “effective”, because it says it is “safe”, it would suffice to “collect a sample of 500 cases, of different ages, in different jurisdictions. “How long would it take to get the final results?” One month, “the infectologist is encouraged to say. This would include a signed consent for scientific research.

Could it also be combined with AstraZeneca? Lopez says yes – always if it is tested before, “because there is no published proof” -, but only by professional intuition, by an alliance that was announced in 2020 and that it did not materialize, at least in the public sphere, between the Gamaleya Institute in Moscow and the Oxford / Astrazeneca team.

“They were going to work together, share the two formulas, make a better vaccine out of this union. So I feel like they have similarities in production that could lead to their eventual combination,” he remarks.

This week, doses of Sinopharm Can it be combined with Sputnik or AstraZeneca? “I would not combine them with inactivated virus, with Sinopharm. Because the Chinese vaccine does little to stimulate memory, Darla T cells would not produce the desired stimulus. With Sinopharm, there are no studies against the Delta variant, even “.

In the middle of these consultations for the note, López asks to get back to the central point: “Give emergency second doses of Sputnik V to the group of people over 60 years old, who were among the most vaccinated with this formula more than 3 months ago, because does not reach a dose. Although the Delta is not in community circulation, it can be overnight. And the new variant discovered in Brazil has the potential to evade immunity for one dose. “

the 78% of deaths It occurs in this group, according to the latest data from the Argentine Society of Intensive Care (SATI).

MG