December , 2020
Vaccination of 910 million needed for ensuring herd immunity in India
11:31 am

B.E. Bureau

Vaccine was probably the most awaited word of the year 2020. Now that it has finally arrived in various countries, there are some unanswered questions.

BE’s Saptarshi Deb spoke to Dr. Paramita Basu, Associate Professor, Department of Pharmaceutical and Biomedical Sciences, Touro College of Pharmacy, New York, the United States of America, regarding the vaccination process.

Q) Indian authorities have said that they are planning to use 600 million vaccine doses to the most vulnerable sections in the next six-eight months. Do you think this will be a significant step in breaking the chain in the Indian context?

A) No. To break the chain of viral transmission it is essential for at least 70% of the 1.3 billion strong Indian population to acquire immunity to the Covid-19 virus. Numerically, this amounts to 910 million people. Since all the vaccines under trial that show promise need two doses, this would necessitate 1820 million doses of vaccines to achieve sufficient vaccine coverage. 600 million vaccines will be enough to vaccinate only 300 million Indian nationals, out of the 910 million needed for ensuring herd immunity.

Q) Are there any risks associated with taking the vaccine pertaining to individual side effects?

A) Before receiving the approval for emergency use, pharmaceutical companies must provide evidence that their vaccines are safe. A team of experts from the US Food and Drug Administration (FDA), CDC’s advisory committee on immunisation practices and other agencies review the data on safety and efficacy before recommending them for use. Additionally, a team of experts at the Central Drugs Standard Control Organisation (CDSCO), which is the Indian regulatory body for pharmaceuticals and medical devices, the Drugs Controller General of India (DCGI) as well as the Indian Council of Medical Research (ICMR) will also review available data to ensure that any vaccine made available to our employees and patients is safe and effective.

Based on Pfizer-BioNTech vaccine trial reports, most people are unlikely to have severe allergic reactions to the vaccine but the shots might come with temporary side effects such as fever and muscle pain - which is an indication that the immune system is doing its job. But the likelihood of getting these temporary side effects might be higher than people expect, according to some recent reports. While researchers haven’t found serious safety issues with the vaccines, they do come with possible side effects mostly of mild to moderate severity, including fever, fatigue, chills, headache, muscle pain, joint pain and arm pain, redness or swelling at the injection site. Side effects tended to be more frequent after the second dose. In the case of Pfizer-Biontech’s vaccine, up to 4.6% of those who received the vaccine reported severe side effects.   

In its phase three clinical trial, the vaccine was generally well tolerated with no serious safety concerns. However, a small proportion of participants in the trials of the Pfizer and BioNTech vaccine had side effects such as vomiting and swollen lymph nodes. Researchers identified four subjects who experienced bell’s palsy, or temporary paralysis of facial muscles. Pregnant women and women trying to conceive were not included in the first round of clinical trials.

The Moderna vaccine appeared to be generally safe, though some subjects developed headaches and other mild to moderate reactions. The vaccine was found to be 94.1% effective in preventing severe disease in the clinical trial. A review of a late-stage Moderna trial found severe side effects including arm pain in 2.7% of participants after the first vaccine dose. Severe side effects after the second dose included fatigue in 9.7% and muscle pain in 8.9%, while 5.2% experienced severe joint pain and 4.5% had severe headache.

Q) What can be the expected societal benefits in India of the planned vaccination process?

A) Covid-19 vaccines are being carefully evaluated in clinical trials and will be authorised or approved only if they make it substantially less likely to get Covid-19 after receiving the vaccine.  Based on what we know about vaccines for other diseases, and the available clinical trial data, experts believe that getting a Covid-19 vaccine may help keep us from getting seriously ill with severe and life-threatening disease symptoms even if we do get Covid-19. Covid-19 vaccination will be a safer way to help build protection. Covid-19 can have serious, life-threatening complications, and there is no way to know how it will affect each individual. Each infected person could spread the disease to friends, family, and others around them. Covid-19 vaccination will help protect individuals by creating an antibody response without having to experience sickness. Wearing masks and social distancing help to reduce our chance of being exposed to the virus or spreading it to others, but these measures are not enough. Vaccines will work with our immune system so it will be ready to fight the virus if we are exposed.

Whether people who have already been vaccinated can still transmit is not fully known yet. Based on our experience with other vaccines and early data from the Covid-19 vaccines, it is likely that people who are vaccinated will have enough immunity where they will not pass the virus to others if exposed - but this is not completely certain.

Q) What are the risks associated with not taking the vaccines?

A) There are risks associated with delaying, skipping, or rejecting the Covid-19 vaccine. With the decision of taking the vaccine, comes an important responsibility to protect your child’s life, or the life of others in your family or community from Covid-19. People of all ages are susceptible to illness from Covid-19. While we continue to learn more about Covid-19, currently CDC identifies persons at increased risk of severe Covid as older adults, with risk increasing as age increases; and persons with cancer, chronic kidney disease, Chronic Obstructive Pulmonary Disease (COPD) and for people in an immunocompromised state for treatment or medical conditions, with obesity and with serious heart conditions in addition to some more conditions.

Sars-Cov2, the virus that causes Covid-19, presents a number of complicated issues, compared to other vaccine-preventable diseases. First, we are unsure how long the immunity lasts. Based on other severe coronavirus infections, it probably lasts months to years, but not lifelong. Immunity may also be less protective in patients who had the mild or asymptomatic disease. If immunity is not long lasting, or if people with mild infection do not develop immunity, herd immunity without a vaccine cannot be achieved. Covid-19 also has much higher rates of severe illness than many other viral infections with up to 15% of infected people being hospitalized and mortality rates estimated at 0.5 to 1%. These rates are 10 times higher than seasonal influenza.

Assuming immunity is long lasting, to achieve herd immunity in India without a vaccine would likely require more than 900 million Indians becoming infected. Even if mortality rates are at the low end of the estimates, there would be more than a million deaths. For every death, there are many more hospitalisations and ICU admissions. Patients who are not hospitalised can still have severe illness and be debilitated for weeks.

Those who believe herd immunity can be achieved through the natural course of infection are misguidedly thinking that the virus just needs to run its course and it will be gone, especially after the vaccine is in use and a section of the population has already been vaccinated. One glaring problem with that idea is we don’t know that people are immune once they’ve been infected.

Q) What will be the effective time period of this vaccine? Will it need to be repeated after specified time periods?

A) Health care professionals and researchers are still learning about Covid-19 and new information is being discovered nearly every day. Because Covid-19 is still a relatively new virus, it is difficult to know exactly how the virus affects the body in the long-term and how long immunity from the natural infection lasts. Therefore, it is also difficult to predict how long a vaccine will provide protection against the virus. As the vaccines are administered and new information is gathered, additional data about how long it will protect against the virus will be made available. Whether the vaccine needs to be given annually, or is it needed only for this year, is not known at this time. Scientists are continuing to collect data about long-term immunity to this virus. Regarding vaccination, we won’t know how long immunity lasts until we have a vaccine and more data on how well it works.

Q) Can you please elaborate on the infrastructural pre-requisites of this vaccination drive?

A) The Covid-19 vaccine rollout will be one of the largest and most complex health initiatives in our medical history. Researchers say information on who got what vaccine and the effect they are having is critical to monitor the safety and effectiveness of the process - even after the vaccines have been approved. It will be crucial for governments to monitor accurately who gets inoculated, particularly because many vaccines are expected to require multiple doses. Widespread tracking would also enable health officials to detect any adverse reactions, which is important because the vaccines are being developed much faster than usual.

When individuals in the US begin receiving the vaccines, they will receive a vaccination card telling them which vaccine they received, when and where it was administered, and when the next dose is due. Vaccine recipients may also opt into a smartphone-based survey and reminder system. Immunization records will also be kept in state registries and maintained as electronic records through health systems and pharmacies. Reminding people when it’s time to get the second shot will be important to ensure the vaccine is as effective as possible. Data from the recent FDA review of the Pfizer-BioNTech vaccine shows that the first dose of the Pfizer vaccine offers strong protection.  However, the efficacy may increase by roughly 40% with the second dose.

In the Indian context, the government health officials may require healthcare providers to report who gets a coronavirus vaccine to the country’s register, but this presents several challenges to authorities, including limitation of resources and personnel as well as accuracy and security of the patient’s health data.  But in view of the widespread use of mobile phones in India, when Covid-19 vaccines are ready for the general population, user-friendly digital programmes or a mobile phone-based app could help to monitor the safety and effectiveness of the vaccines while also allowing each individual to easily store their vaccination history on their phones.

In the US, the CDC and other federal agencies will introduce new surveillance methods including a smartphone-based platform called v-safe. People can opt into the service voluntarily when they receive a vaccination. Through the programme, people can report adverse effects of the Covid-19 vaccination and receive text messages reminding them when and where their next dose is scheduled to be administered. In Canada, the newly developed platform canimmunize, which is a free phone app that allows individuals to store their vaccine history and keep it all in one place, almost like a digital version of the old yellow vaccination cards, is well-poised to help users with the vaccination process. 


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