It is nearly one year since the Covid-19 pandemic started to spread. Over six vaccines against the novel disease have already been approved for Emergency Use Authorization (EUA) across the world. This has never happened in our history before. What used to take decades happened in a year! Many things happened at once to make this possible. However, people have many questions, not only because the vaccines have arrived within one year, but also many more voices raising valid and invalid questions fueled more so by the reach of regular and social media. The article tries to bring sanity into the subject by answering some frequently asked questions in this regard
What are the differences between various vaccines?
The core objective of the vaccines is to submit the antigen (viral proteins) to the human body’s immune system that develops immunity (antibody and cell mediated) against the virus. These proteins can be expressed outside and injected as a vaccine (component vaccine being made by Biological Evans, India), can be expressed through mRNA that codes for specific protein (Pfizer and Moderna), can be expressed through DNA fragment inserted in another virus vector (Adenovirus) that codes for the protein (Oxford Astra-Zeneca vaccine or the Covishield vaccine being manufactured by Serum Institute India, Sputnik-V vaccine from Russia being tested in India by Dr.Reddy Labs with manufacturing arrangement with Hetero Drugs), and inactivated whole virus (Covaxin by Bharat Biotech and Sinovac from China). Except mRNA-based vaccine platform which is being tested for the first time, all other platforms have been well tested over many decades. Other major differences are with reference to the temperature at which these vaccines have to be stored (Pfizer at -70oC, Moderna at -20oC, and all others at normal refrigeration temperatures of 2 to 8oC), adverse events, effectiveness, and cost.
What is the meaning of Emergency Use Authorization?
Covid-19 pandemic continues to infect and kill people across the world. Many countries are undergoing severe economic distress. Children are unable to go to schools. Given this situation, regulatory bodies invoke emergency use authorization based on data submitted with regards safety and effectiveness being addressed in phase 1, 2, and 3 trials. Safety of every approved vaccine has been clearly established in thousands of volunteers who participated in clinical trials. Ability to induce immunity (both antibody and cell mediated) is also clearly established by all the approved vaccines and the results have been shared in peer-reviewed journals. Ability to prevent development of Covid-19 illness is established in most of the approved vaccines and varied from 60 to 95% (WHO has set the effectiveness rate of ~50% point estimate for approval). Few countries such as India, China, and Russia have issued emergency use authorization while phase 3 trials are still ongoing based on phase 1 and 2 trials data and limited data from phase 3 trials with stringent conditions to submit additional data from the ongoing trials. All the approved vaccines will have to keep submitting long term follow-up data to assess their long-term safety and effectiveness. Regulatory bodies will issue full authorization only after all the trials are completed as specified in their trial protocols.
Who should take the vaccine?
All people above 18 years of age should take the vaccine. Since vaccines are not tested in pregnant women, only those with comorbidities can opt to take with full understanding that the safety of the vaccine is not tested in pregnancy. Some vaccines are being planned to be tested in children. It may be prudent to avoid vaccinating children until data from children is available. Since vaccines supplies may not meet everyone’s need, priority is given to healthcare personnel, frontline workers, elderly (above 50 years), and younger people with comorbidities.
Why should one take the vaccine?
At personal level, it is to protect themselves from developing Covid-19 illness with its attendant morbidity and mortality. At public level, it is to achieve ‘herd immunity’ in order to stop the pandemic. It is estimated that ~60 to 70% of the population should have immunity (either through vaccination or natural infection) for the pandemic to stop. Though it is voluntary, it is the responsibility of everyone to stop the pandemic so as to bring back normalcy into everyone’s lives!
When to take the vaccine?
Vaccine can be taken as soon as it is available as per the priority list stipulated.
Should people with prior Covid-19 infection take the vaccine?
Major institutions across the world have recommended people to get vaccinated irrespective of their prior infection status. However, they can volunteer to get vaccinated later so that those who do not have prior infection get a chance to get protected, since prior infection also imparts immunity. People who got recent Covid-19 illness are advised to wait for 14 days after the onset of symptoms for taking the vaccine.
How long will the vaccines work?
Most of the vaccines have only short-term data from the ongoing trials. Hence, we have to wait until sufficient follow-up data is made available. People who have been vaccinated will be under long term surveillance for any unreported adverse events and any recurrences of Covid-19.
Will the vaccines protect against the new strains reported from UK and South Africa?
There are no reports of reinfection of the people with prior Covid-19 illness with the new strain suggesting that the existing immunity from previous strain may be protective. Vaccine companies are evaluating efficacy of their vaccines against the new strain in the lab, in animals and in trial volunteers. We need to watch for reports from national and international public health bodies for any loss of protection against the new strains.
Where should I look for authentic information on Covid-19 and its vaccines?
Various national and global health institutions are updating their websites with latest information as and when it is available after thorough verification. These include WHO, NIH (USA), Johns Hopkins Public Health Institute (USA), CDC (USA), ICMR (India) etc. People should be wary of unverified news on social media and regular media.