Is it okay to combine Covishield and Covaxin for increased immunity?
The two leading indigenous vaccines used to immunize the country’s vulnerable population are Covishield (Oxford-Astrazeneca) and Covaxin. While both vaccines have proven to be highly effective and safe, expert committees are now considering combining the doses of the two traditional vaccines to maximize benefits and provide long-term immunity.
While mixing and matching coronaviruses is not entirely novel, the combination of two vaccines of the same type is. The first such test in India will be approved for use as well.
So far, what has been proposed
The Vaccine Subject Expert Committee (SEC) has proposed the use of combined doses of Covishield, manufactured by the Pune-based Serum Institute of India (SCI), with Covaxin in collaboration with the Hyderabad-based Bharat Biotech. We recommend that clinical trials be permitted at the Christian Medical College in Vellore.
How are they different?
The main vaccine applicants approved for use in India are Covaxin and Covishield. Covaxin has not been used on a global scale, despite being approved for use in other countries. While both vaccines were created using traditional vaccine-making technologies, they differ slightly in comparison. Astrazeneca is a genetically modified (weakened) version of the common cold virus that has been genetically modified to match the coronavirus (but cannot cause the illness).
Why do experts prefer combining vaccines?
A thorough investigation and discussion of mixing and matching vaccine regimes, including COVID-19 experimental vaccines, has taken place. The primary reason that many medical experts now support administering one vaccine brand on the first dose and another brand on the second dose is that it combines the best benefits of the two vaccine doses to combat decreased efficiency rates and to trigger better immune responses. While the effects of these vaccines are seriously jeopardized by coronavirus variants, COVID-19 mixed and complementary vaccines may address safety concerns while potentially resulting in high efficiency rates.
What does research from other countries suggest? Have any other vaccines been mixed in?
The combination of Covaxina and Covishield isn’t the first time such a policy has been contemplated. Since mutant strains of the virus began to circulate, and waning immunity with some vaccines became a source of concern, the mix and match regimens have been subjected to a number of clinical studies. However, there is currently no relevant or substantial data to support the safety.
It has been shown that using two different vaccine doses can increase protective response, build immunity, or provide a better response than receiving two doses of the same vaccine. A clinical trial, for example, found that combining Pfizer and Astrazeneca (Covishield) vaccine doses was superior to receiving two Pfizer or Astrazeneca vaccine doses alone. Some proponents of the policy argue that such a system would give people more options and allow them to get the vaccine (or dose) that is best for them.
Has such a study ever been conducted in India?
While the proposed study has yet to be approved, some people in India have already received doses of both vaccines at different intervals (accidentally or for clinical reasons). At least 20 people from a district in Uttar Pradesh were given Covaxin, followed by Covishield. While there was some difference in the antibody response, no major side effects were observed.
Will it work against the Delta variant of SARS-COV-2?
The spread of the second wave in India was aided by the Delta variant of SARS-COV-2, which is thought to have originated in India. It also resulted in an increase in infections in those who had been vaccinated (partially or fully), because it was able to easily evade many of the antibodies put in place by the vaccine.
While the variant continues to spread at an alarming rate around the world, and similar harmful variants are expected to emerge, it is believed that combining vaccines will allow for greater immunity that works against the variant and results in a longer-lasting antibody count, which could protect individuals. Experts believe that combining vaccines based on two different technologies may also cause the immune system to develop a broader response in the case of variants.
Is There any Risk in Doing So?
Although there are numerous benefits, some people are unaware of the policy change and its future potential, citing a lack of available data and concerns.
A mixing policy would not only allow for the safekeeping of two different doses and equitable distribution, but it would also be devoid of data to support the same and determine whether the combination of experimental vaccines COVID-19 is truly effective. Furthermore, the World Health Organization has labeled the policy as “threatening” and “unnecessary,” implying that the experiment may contribute to the depletion of resources for countries that do not have enough.