In many European countries, including Germany, France, Sweden, Norway and Denmark, authorities are now advising younger people, who were previously given the AstraZeneca vaccine as a first dose, to take an alternative vaccine as their second vaccine jab. Following multiple cases of a rare side effect of a blood clotting/bleeding condition in vaccinated individuals, the authorities decided to stop the administering of the vaccines. Since then many European countries are using mix and match vaccine schedules.
Canadian health officials have also announced that Covid-19 vaccines will be mixed and matched in order to ensure a quicker roll-out of the national vaccination programme.
According to a UK study published in the Lancet, 830 people over the age of 50 were asked to get either the Pfizer or AstraZeneca vaccines first, then the other vaccine later. The study found that those who received mixed doses showed mild to moderate symptoms following their second dose as opposed to people who received non-mixed doses. However, as per experts, the symptoms were short-lived.
Another Spanish study found that people who received mixed doses had higher antibody response 14 days after receiving the Pfizer shot, following the first dose of the AstraZeneca vaccine.
In addition, experts found that these antibodies recognised and inactivated the SARs-COV-2 virus in lab tests.