May 10, 2021 10:50:45 am
The covid-19 virus has a tendency to mutate rapidly. A variant has one or more mutations that are different from other variants in circulation. However, not all variants are significant. Variants of concern are those which are highly infectious and virulent (disease-causing ability) and are less effective in treatment and vaccination.
Two vaccines are currently administered in India to prevent the spread of Covid-19 infection — Covishield (ChAdOx1-nCOV) and Covaxin (BBV-152). “Now, we should focus on mass vaccination and increase the compliance of vaccination,” said Dr Gitali Bhagawati, consultant and head, Department of Microbiology and Infection Control, Dharamshila Narayana Superspeciality Hospital.
Composition and manufacturer
She went on to explain that Covishield is a Recombinant Chimpanzee Adenovirus vector vaccine (Covishield) encoding the SARS-CoV-2 Spike (S) glycoprotein with technology transfer from AstraZeneca/Oxford University. Recombinant virus vector acts as endogenous antigen which helps in the production of T-cytotoxic cells, thereby leading to the establishment of cell-mediated immunity. The Adenovirus vector vaccine induces antibody reaction against spike S1 fragment, production of SARS-CoV neutralising antibodies and T-cell proliferation against the N protein.
Covaxin has been developed by Bharat Biotech in collaboration with the Indian Council of Medical Research and the National Institute of Virology. Covaxin is Whole Virion Inactivated Corona Virus Vaccine, and is developed on Vero cell platform. These kinds of vaccines are produced by neutralising the pathogen as a whole which ceases the ability of infection and replication of this virus but retains the immunogenicity, thereby inducing immunity.
Both the vaccines are safe as per clinical trials of these vaccines and as mentioned by the concerned authority. “The efficacy of Covishield vaccine has been found to be approximately 73 per cent. Phase 3 interim analysis of Covaxin result estimates 78 per cent efficacy rate against mild, moderate, and severe Covid-19 disease,” she told indianexpress.com.
Vaccines covering variants:
Recently, researchers at the Hyderabad-based Centre for Cellular and Molecular Biology (CCMB), a Council of Scientific and Industrial Research (CSIR) lab, have found that Covishield vaccinated sera and convalescent sera both have protection against the double mutant variants (B.1.167). An ICMR study has also found that Covaxin is effective in neutralising SARS-Cov-2 variants: B.1.1.7 (UK variant), B.1.1.28 (Brazil variant) and Double mutant variant B.1.617.
Some important points to remember:
*Immediate vaccination does not give immunity against Covid-19. That is why it is advised to continue Covid appropriate behavior (CoAB) before, during, and after vaccination. Adequate immunity develops only after few weeks of the second dose of vaccination.
*Vaccination does not rule out the possibility of Covid infection. However, it can reduce the severity and mortality amongst Covid infected patients.
*Vaccination is not an alternative to treatment during Covid infection. If someone develops signs and symptoms of Covid, he should refrain from vaccination during that period. At that moment, early testing followed by early symptomatic treatment is advisable.
*Covid infection itself gives some natural immunity against Covid-19 which varies from person to person. That is why, the first dose of vaccine can be taken few weeks after Covid infection.
Can we get first and second doses of vaccine by different manufacturers?
Every effort should be made to complete the vaccine series as first and the second dose from the same manufacturer, said Dr Bhagawati.
Clinical trials in some countries are looking at whether we can have the first dose from one vaccine and a second dose from a different one. “Boosting with different kinds of vaccines may mount greater immune response which can help to counter immune escape phenomenon of variants of concerns. However there is not enough data yet to recommend this type of combination,” she said.
As per Centre for Disease Control and Prevention (CDC), in exceptional situations where a patient received the first dose of an mRNA COVID-19 vaccine but is unable to complete the series with either the same or different mRNA COVID-19 vaccine, a single dose of Janssen COVID-19 vaccine may be considered at a minimum interval of 28 days from the mRNA COVID-19 vaccine dose.
Common side effects from vaccination:
According to Dr Bhagawati, the most common side effects are local pain, redness, and swelling, fever, chill, tiredness, headache, muscle pain etc. which is even common with almost every disease’s vaccine. Some people may not have any side effects at all.
Adverse event following immunization (AEFI) related to vaccination is any untoward medical event that follows immunization and that does not necessarily have a causal relationship with the usage of the vaccine. “Any AEFI should be immediately reported to healthcare authority,” she mentioned.
Vaccination is the need of the hour looking at the increasing severing and rising mortality of Covid-19 in second wave.
Apart from vaccination, we should not forget the 3 Ws of CoAB to win the battle with unseen enemies: Wash hands frequently. Watch for social distancing and wear mask/s in an appropriate manner.
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