Updated: May 20, 2021 7:08:28 am
A Spanish study has found that a first dose of AstraZeneca’s coronavirus vaccine, followed by a dose of Pfizer’s vaccine, is highly safe and effective. That is the preliminary results of a clinical trial, Combivacs, presented on Tuesday by the Carlos III Health Institute in Spain.
The study recruited 673 participants under age 60 who had already received a dose of the AstraZeneca vaccine and were at least in their eighth week after that dose. A second dose of the Pfizer vaccine was given to 441 participants, while the control group of 232 did not get this second dose.
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In people who got both doses, IgG antibodies in the bloodstream was found to be 30-40 times higher than those who received only the one AstraZeneca dose. The presence of neutralising antibodies, too, rose seven times after a Pfizer dose, according to a Reuters report. For comparison, in those who receive two AstraZeneca doses, the presence of neutralising doses has been observed to double after the second shot.
In participants who received both doses, side effects were mild, and related to injection site discomfort. The most common side effects were headaches (44% of all cases), malaise (41%), chills (25%), mild nausea (11%), mild cough (7%), and fever.
The study comes amid acute vaccine shortages in various countries. With limited vaccine supplies, not all countries have the option to choose which kind of vaccine they can offer to the public.
In India, as in many other countries, mixing of two different vaccines is not recommended in the national guidelines. India is administering two vaccines, Covaxin and Covishield, which is a version of AstraZeneca’s vaccine.
A similar study has been under way in the UK since February. The country’s Vaccine Taskforce provided £7 million for a vaccine trial meant to study the effectiveness of alternating doses of vaccines. This study will assess eight different combinations of vaccines, which also include vaccines made by AstraZeneca and Pfizer.
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