He, however, noted that the only vaccine available in the country at the moment was the AstraZeneca vaccine despite the emergency use approval of Johnson & Johnson and Pfizer vaccines by the National Agency for Food Drug Administration and Control.

“You can only administer what you have. Approval is one thing, acquisition is another. Nigeria has neither acquired J&J nor Pfizer vaccine, whether through purchase or donation.

“Yes indeed, from preliminary results, vaccine mix and match is safe and even more likely to produce a more robust immunity than matching same vaccines only, with no mix.

“The more people we vaccinate, the more will develop immunity against the virus and the more likely our chance of controlling the outbreak and better able to prevent a possible third wave. But remember vaccination alone will not solve the problem. We must still adhere to the non-pharmaceutical interventions, wear your mask, avoid large gatherings, keep a safe distance,” Tomori said.

A Professor of Virology at the University of Ibadan, David Olaleye, however, had a different opinion, saying a combination of vaccines may not happen in Nigeria.

“I don’t think a combination dose is likely to happen in Nigeria because what we know today in vaccinology is that when you prime with a particular antigen which is the vaccine, you boost with the second dose of the same vaccine. You can only boost effectively with the same antigen. You can boost with a different antigen but immunologically and from what we know today, it is unlikely to give you the same level of response as using the same type of vaccine.

“There are what we call memory cells. The cells that have been exposed to the antigen initially but are resting in the bone marrow or the location of the cells, are there. The next time that the individual or the body is exposed to an antigen they’ll recognise, there will be a quick, faster and higher cellular response or even better than the first one. But these case of combination doses that is still being explored is good for study and is still experimental.

“If the same vaccine is not being used, there will be what we call cross-reaction. With different antigens, there will be cross-reactivity compared to when you use the same type of vaccine to boost what you have been given before. In terms of our context in Nigeria, I will not bother because it is unlikely to happen because of the vaccination plan here.”

No fewer than 2,265,805 eligible Nigerians have received the first dose of AstraZeneca vaccine, while 1,175,341 have received the second dose as of June 28.

source: Medicalworldnigeria