Tuesday, June 15

Combining Covid-19 vaccines increases adverse effects




Combine vaccines, as the Spanish government is doing with the clinical trial CombivacS that discusses the possible protective effect and safety of giving a dose of the vaccine BioNtech/Pfizer to people who have already received a first dose of AstraZeneca vaccine, you can increase the reactogenicity, that is, the mild to moderate adverse effects.

They are study data Com-COV, which are ahead today in
«The Lancet»
, trial comparing mixed dosing schedules of vaccines Pfizer / Oxford-AstraZeneca, and that shows an increase in the frequency of mild-moderate symptoms in those who receive either of the two dosage schedules. However, the adverse reactions were of short duration.

The study researchers Com-COV directed by
Oxford University
, today presented preliminary data revealing more frequent mild to moderate reactions.

The trial recruited 830 volunteers aged 50 and over in England to evaluate the four different combinations of first dose and booster vaccination: first dose of AstraZeneca vaccine followed by a booster with Pfizer or the same vaccine, or a first dose of Pfizer followed by a booster with AstraZeneca or Pfizer.

In April, researchers expanded the program to include vaccines Modern and Novavax in a new study (With-Cov2). The volunteers would have received the first dose with the Oxford-AstraZeneca or Pfizer vaccine, and were then randomly assigned to receive the same vaccine for their second dose or one dose of the vaccines produced by Moderna or Novavax.

Each of the six new “arms” of the trial aimed to recruit 175 candidates, adding another 1,050 to this program.

Both studies are designed as studies of ‘non-inferiority’, that is, trials intended to show that combining is no worse than not combining, and will compare immune system responses with responses obtained in previous clinical trials.

In research published in
«The Lancet»
, report that, when administered at a four-week interval, the guidelines ‘mixed‘, Pfizer-BioNTech and second dose of Oxford-AstraZeneca or Oxford-AstraZeneca plus Pfizer -BioNTech, more frequent reactions occur after the second dose of’ booster ‘than standard non-combined regimens.

Adverse reactions in study patients were short-lived

Matthew Snape, from
Oxford University
and lead investigator of the trial, notes that, although this is not the aim of the study, “it is important that we inform the population, especially since these mixed dose regimens are being considered in several countries. The results – he continues – suggest that this mixed dose vaccination scheme could cause an increase in absences from work the day after vaccination, and this is important to take into account when planning the immunization of health professionals ».

But he emphasizes that there are “no signs that suggest a greater risk in terms of safety, although we cannot say whether the immune response will be affected.” In this sense, they hope to publish these data in the coming months.

Meanwhile, Snape notes, “We have adapted the study to assess whether early and regular use of paracetamol reduces the frequency of these reactions».

They also noted that because the study data was recorded on participants 50 years or older, there is the possibility that these reactions are more frequent in the younger age groups.

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