When the vaccination campaign had just started, the main recommendation was: "The best vaccine is the one you can get right now". 

And although there were political nuances, this recommendation really made sense: all WHO-approved vaccines protect well against death and severe cases, and this is what we primarily vaccinate against.

However, with the introduction of the booster dose, new recommendations have emerged.

According to the Ministry of Health of Ukraine, mRNA vaccines are preferred for booster vaccination. These are vaccines such as Pfizer and Moderna.

There are also narrower recommendations: for example, if you have the first two doses of the inactivated Coronovac vaccine, then Pfizer is advised to do the booster. 

Is it possible to choose a vaccine and does it make sense?

In general, no.

If you are a person without special medical contraindications, it is best to get the mRNA vaccine that is most available. The immunologist advises focusing on which vaccine provides the greatest protection. 

There are studies that show that those who have received the first two doses of Moderna will get the highest protection if they choose Moderna as a booster. 

If your first two doses are inactivated vaccines (in Ukraine it is Coronovac), then some data have shown that:

Pfizer booster dose after two doses of Coronovac increases protection from 54% to 95%;
AstraZeneca dose from 54% to 94%; 
Coronovac booster dose from 54% to 74%. 
But this study does not take into account the Omicron variant. This study shows protection against Alpha and Delta variants, which is not so relevant anymore. 

 

If theoretically you suddenly find yourself in a situation where it is time to take a booster dose and mRNA vaccines are not available, you can choose any other vaccine.

Recently, the Ministry of Health has updated the vaccine administration regimens.

Now you can be vaccinated with the AstraZeneca vaccine after the first dose of Pfizer or Moderna.

Also, people who have been vaccinated with CoronaVac will be able to receive a second dose of AstraZeneca, Pfizer, or Moderna.

And those who received the first dose of AstraZeneca can still get a second dose of Pfizer or Moderna.

Previously, AstraZeneca was not used for the second vaccination after mRNA vaccines.

Also, the Ministry of Health did not recommend mixing the CoronaVac vaccine with other drugs but recently updated this data.

Now such vaccine combination schemes can be used for booster vaccinations.