A medical worker prepares a vaccination against the coronavirus disease (Covid-19).(Reuters)
A medical worker prepares a vaccination against the coronavirus disease (Covid-19).(Reuters)

FAQs about immunisation answered

Here are all your questions about immunisation and vaccines answered
Hindustan Times, New Delhi | By hindustantimes.com
UPDATED ON JAN 01, 2021 03:17 AM IST

How safe are vaccines?

The three leading candidates have not shown any significant adverse reactions among the tens of thousands of volunteers who were vaccinated during the large-scale trials. The vaccines have been tested in healthy people and more data from those in vulnerable groups is being derived. The regulatory approval processes, in India as well as advanced markets such as the US and the UK, closely scrutinise adverse effects and a vaccine is approved only when it is safe and effective by design. Thorough checks are also in place on the production side as well as during logistics.

What about the allergy reactions reported from other countries?

Cases of anaphylaxis — a severe allergic shock — have been reported from a handful of people from among the close to three million people vaccinated across the world. Experts have since determined that these were because the individuals were allergic to particular ingredients in the vaccine similar to how people might have specific food allergies but be able to tolerate most other things. On December 30, UK authorities updated their advisory to say that only people with history of known allergies to any of the vaccine ingredients must exercise caution and that there is no risk for others.

In India, recipients will be monitored for 30 minutes for signs of an allergic reaction, which can normally be addressed quickly.

How soon can I get a vaccine?

If you are a health worker or in a front line job such as police or the military, then you are among people first in line to receive a dose. After that, people above the age of 50 and those under it but with comorbid health conditions that make them more vulnerable to Covid-19 will be vaccinated. Together, these groups are expected to account for the first 300 million who will need to be given doses. The government has set a tentative target to complete this process by the summer, which means if you fall in any of these categories, you may get it in the next six months. For others, the wait may be longer and there have been talks of allowing private market sales, which could let people buy doses at market rates.

Am I safe after the first shot?

No. People will need to maintain precautions until they get the booster dose, since all three vaccines approved till now involve a two-dose regimen. Once both doses are given, it might take up to two weeks to build protective immunity.

How long will it protect me?

It is still unclear how long immunity to Sars-CoV-2 lasts, whether it is triggered by natural infection or through a vaccine. Research has shown that antibodies could last around six months, which makes chances of reinfection low. But another component of the immune system — the adaptive immunity that also includes memory cells — may remember the infection for years, as it does with coronaviruses. This, scientists estimate, can help avert a serious disease later on, even if it doesn’t stop a reinfection.

Will the new variant make vaccines ineffective?

The vaccines target the spike protein, which includes several of the 17 changes in a new mutation has spread widely in the UK and is believed to be more transmissible. Experts, however, say the changes are not significant enough to make the vaccines obsolete. All major vaccine developers are saying they are carrying out additional tests to determine for sure. But, even if a future variant does, the vaccines can be re-engineered quickly to fight off any new mutation that reduces their efficacy.

Is one vaccine better than the other?

Efficacy rates among the leading vaccines have had varying levels in clinical trials. Their early assessments also showed that some such as the mRNA platform vaccines are better than others, such as those that use the inactivated virus platform. But all of these appear to be above the 50% bar set by regulators for efficacy. In the initial phase of the roll-out, experts believe that any vaccine with an efficacy level of above 50% will help in slowing down the pandemic.

How quickly can vaccines lead to herd immunity?

This depends on the population of the country. As on December 30, Israel had vaccinated the most number of people per capita, with more than seven people per 100 having gotten the shot, Our World in Data statistics showed. In comparison, the per 100 people vaccination in the US, which delivered 2.13 million doses as of December 28, was a mere 0.64. For a country like India, hence, herd immunity may take longer to achieve. In the mean time, the primary objective would be to gives vaccines to those most at risk of death or hospitalisations — a cohort that largely includes people in higher age brackets and with comorbid conditions.

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