How mixing vaccines could help end India’s second-dose crunch. Is it safe to take a gun for two different vaccines Covid? Do mixed vaccines protect more or less? Several countries have already begun screening tests when the Indian government says it will not change its vaccination agreements until mixed vaccines are scientifically supported. If the tests are successful, you will not need to delay your second dose just because a specific vaccine is not available.
Some countries have already adopted such standards of ‘mixing and matching’ in emergencies, with early test results suggesting that a particular combination is safer and more likely to work.
What mixing drugs look like
All approved vaccines except of the Johnson & Johnson which requires two doses. Usually, the first dose triggers the immune system to detect the virus and the second to increase its detection and response.
To combine vaccines, mention the first dose of an antiretroviral drug like Oxford-AstraZeneca’s Covishield and the second dose of mRNA jab like Pfizer-BioNTech, called ‘heterologous prime-boost’ and you can train the immune system to detect the virus in more than one way.
The Sputnik V of Russia is a ‘combination’ vaccine by design. The first dose uses a harmless cold adenovirus (Ad26) to deliver genetic instructions for cells to produce the coronavirus’s spike protein. The second is to do it with a different adenovirus (Ad5), to avoid an attack of the immune system that now sees Ad26.
This machine works – Sputnik V has a 91.6% performance rate, similar to the Pfizer and Moderna mRNA vaccines, even though it is an HIV vector like Covishield.
Other studies in mice have also shown that the combination of drugs produces a better immune response, but researchers will still answer results from large human trials.
UK research finds mixing Covishield, and Pfizer is safe
Oxford Vaccine Group conducts a Com-CoV trial in the UK to study a combination of the first post Pfizer or Covishield followed by a second dose of Moderna or Novavax. It will be the largest study with at least 800 volunteers aged 50 and over, with a capacity of 1,000 more.
Preliminary results, according to a letter from researchers published in The Lancet, indicate that a combination of Covishield and Pfizer may produce a strong immune response – pain or swelling in the injection site, fever and headache – after a second dose of two doses of the same vaccine. But this response was not difficult or long lasting and there were no other safety concerns.
However, it is not clear whether the combination affects efficiency. More details are expected later this month.
Dr Matthew Snap who is a lead researcher of study said that If they can show that these mixed systems create an immune response similar to normal programs, and without a significant increase in vaccine mutations, this will allow more people to complete their Covid-19 vaccine studies more quickly.
Can combining vaccines improve immune response?
Some experts say that a combination of antiretroviral drugs may better prepare the immune system to fight off a wide range of threats, including new ones.
In a Spanish study involving more than 600 people, 400-odd found the first dose of Covishield followed by Pfizer shooting eight weeks later. They have produced much higher levels of antibodies than others, but it is still unclear whether the Covishield-Pfizer combination works better than the two doses of Pfizer.
Dr V Ravi who is a pathologist and also a member of the expert committee of the Department of Applied Technology said that personally, these vaccines have proven to be safe and psychologically there should be no safety concerns. … By protecting the body, the goal is to go ahead with one dose and the other to increase it. The key question that needs to be answered is whether mixing will affect efficiency.
But in countries where there is a shortage of vaccines, the main impetus for mixing guns is to work, not work. In India, for example, having many safe combinations of vaccines can help intensify vaccination efforts.
“It will provide flexibility in using any available vaccine. Remember, the regulator has given his approval of the same drug in two doses, so a bridge test may really be needed. Therefore the details – whether done in India or abroad – must be disclosed before the regulator here, ”said Dr Ravi.
Countries allow mixing
The UK, Germany and France have already agreed to combine the drugs in ‘different situations’ and several trials, especially for adults, continue to better understand the effects. The US and UK have warned against mixing doses unless unavoidable.
In Europe, concerns about safety around Covishield have prompted Germany and France to recommend young people who have received Covishield first to receive a second dose of mRNA. Some countries await the outcome of the trial before formally recommending the mix.
Some experts say that mixing may be needed over time if the virus evolves into a new species or if limited immunity from a two-drug source requires a booster in the future next year.