South Korea has announced that it will begin a clinical trial into combining the doses of AstraZeneca and Pfizer COVID-19 vaccines to speed up the inoculation campaign in the country. The trial will be conducted on 500 military personnel who have already received one dose of AstraZeneca. Researches will examine their immune response after a dose of the Pfizer vaccine is administered.
A number of European countries and Australia are also considering the commencement of their own mix and match vaccine trials. If the strategy is proven to be safe and effective, it will provide a big boost to the vaccine drive across the globe. A panel of experts on Republic Media Network answered some of the intriguing questions regarding this vaccine 'cocktail' strategy and whether it is safe as well as effective against Coronavirus.
Will mixing vaccines give an effective immune response?
“Definitely,” said Dr Chakra Rao. The first vaccine dose will produce an immune response and the second dose will act over it. So, it will definitely increase the vaccine efficiency and will not have any side-effect, he assured. “I am sure that in the case of India, mixing the two available vaccines – Covaxin and Covishield will have no side effects on the individual,” Dr Rao said.
Do we see a possibility of vaccine mixing in India?
In this period of vaccine shortage around the world, the policy of mixing vaccines makes a lot of sense, for a large population of India, said Dr Bharesh Dhedia.
“We should definitely consider this strategy as it allows the participation of many other companies that are simultaneously producing multiple vaccines in the country. It probably even boosts the immune response to a much higher level than what we have seen with the individual vaccines. Not only will we see better efficacy but we will also be able to overcome the shortage of vaccines through the mix and match response,” he suggested.
What could be the possible side effect of such a vaccine cocktail?
Dr Anil Kumar said, combining two different vaccines with totally different methodologies can often be tricky and have certain side effects on the recipient. Recent studies have found that 35% of the people reported more of side effects like fatigue, fever or headache because they were exposed to the vaccine for the first time, he said.
“In my personal experience, healthcare workers have found that people reacted significantly to the first dose but there were no side effects for the second dose. So, it is advised that both the combined vaccines should not be administered on the same day as people would show certain side effects,” Dr Kumar said.
Is a booster shot required after two doses of vaccine?
Since we have seen a lot of cases of COVID-19 infection and fatalities despite administering both doses of vaccines, a third booster should be the way forward in ensuring safety from the virus, said Dr Bharesh Dhedia
“If a third booster addresses new Coronavirus variant that can possibly escape immunity, it would greatly help in reducing infections as well as death rates among vaccinated individuals. Given the rapid changes in the virus genome, we will probably need yearly boosters in the future,” said Dr Dhedia.
What is the longevity of immunity gained by vaccines?
Technically, vaccination helps in preventing the infection for up to 68 months. Despite that, there remains a possibility of infection among vaccinated individuals, however, the severity of illness is not there, said Dr Anil Kumar. “As the virus keeps mutating, we have to get a booster and we cannot rely on the period vaccine for lifelong,” he added.
Can an intranasal vaccine be taken if an individual has received one dose of Covishield/Covaxin?
Bharat Biotech is working on a new intranasal vaccine against COVID-19. It can be easily combined with the intramuscular vaccine (Covishield/Covaxin) and it will be as effective as other routes, said Dr Chakra Rao.