The Public Health Commission recommends those over 60 years vaccinated with a first dose of AstraZeneca who complete the pattern in 12 weeks with this same brand and not with Pfizer, as it advises minors of that age, since there are not the same risks for both population groups.
This is reflected in update 8 of the Vaccination Strategy published today by the Ministry of Health, which on some occasion had opened the door to give a second dose of Pfizer also to those over 60 years vaccinated with AstraZeneca in the event that, due to the laboratory’s non-compliance with its deliveries, there was no dose of the Anglo-Swedish preparation for everyone.
The document recalls that on May 18, after having extended the regimen from 12 to 16 weeks to those vaccinated with AstraZeneca under 60, and given the positive results obtained by the CombiVacs study, promoted by the Carlos III Health Institute, it was decided to immunize them with a second dose of Pfizer.
A day later, faced with the reluctance of a large number of autonomous communities and the scientific community, It was agreed that those who rejected Pfizer could be vaccinated with AstraZeneca by signing a consent informed “in view of the risk that to collective and individual health would mean that these people would be left without the complete vaccination scheme.”
Without this having supposed – assures Public Health – “a choice of the vaccine in the strict sense”. “The vaccine to be administered cannot be at the request or choice of individuals or health personnel, on pain of undermining the principles and ethical values of the Strategy,” the document insists.
In addition to CombiVacs, the update justifies this decision based on other studies that support the effectiveness of mixing both vaccines.
“In summary, a better neutralizing antibody immune response is observed after the administration of an mRNA vaccine as a second dose after having administered the first dose with Vaxzevria in young people. This response is superior to the administration of the two-dose regimen with Vaxzevria. “, he concludes.
The same is not the case for the group aged 60 to 69 years: “In this population group, the use of Vaxzevria in a two-dose regimen is recommended, with a separation of 10-12 weeks between the two, since the available evidence on the occurrence of adverse events of thrombosis syndrome with thrombocytopenia associated with vaccination, although it exists, is much less than in the population under 60 years of age “.
With what “Therefore, according to current scientific evidence, the safety reasons that led to the indication of a heterologous pattern do not concur in second dose for the minors of that age “.
Until last June 2, in UK they had administered 24.5 million first doses and 15.7 million second doses of Vaxzevria; In total, 372 cases of these thrombi have been detected (200 in women and 169 in men aged between 18 and 93 years) and only 23 after the second puncture. The fatality is 18% with 66 deaths.
In Spain, Vaxzevria is contraindicated in people who have presented thrombotic events with thrombocytopenia or “highly suspicious” but not confirmed after the first dose, as well as in those with a history of having suffered a systemic capillary leak syndrome.
Due to the similarities in its pathogenesis with heparin-induced thrombocytopenia, and until more evidence is available, the administration of adenovirus vector vaccines – also Janssen – is discouraged in people with a history of heparin-induced thrombocytopenia.
On the contrary, the restriction of the use of these two vaccines in patients with conventional risk factors for thrombosis is not contemplated at this time, even remembering “the benefit of vaccination for these patients, given that the disease COVID-19 it is associated, by itself, with an increase in thrombotic events “.