It has been five months since India saw its Covid-19 peak. It continues to manifest a downward trend in newly reported cases ever since. And yet, the recently released national seroprevalence survey suggests that a significant proportion of the population still remains vulnerable, with seropositivity cases nowhere near herd immunity levels for a large part of the country.
The third seroprevalence survey carried out by the Indian Council of Medical Research in 70 districts from 21 states between mid December 2020 to early January this year, has revealed a seroprevalence of 21.4 percent among the sample population. This points to a three times increase since August 2020 and a thirty times increase since May 2020, when the previous rounds of the survey were conducted. This means that nearly one in five Indians had been infected by the SARS-CoV-2 coronavirus until December 2020. This also means that 4 out of 5 Indians may still be susceptible to contracting the virus.
Experts believe that a large proportion of the population remains vulnerable and that vaccines are necessary and there can be no complacency with regards to masks, social distancing and hand hygiene.
What do the seroprevalence studies tell us?
The sero-survey results show that the a large number of cases in India were mild or asymptomatic. These people were never tested even with ramped up testing across the country. As per the study, antibodies to the SARS-CoV-2 virus were detected in 21.4 percent of adults surveyed, and 25.3 percent of 10 to 17 year olds surveyed. This translates to 3.5 percent of infections being detected, reported, and recorded as positive cases. The total positive cases reported in India as on February 11, stood at 10.9 million.
Seropositivity was highest in urban slums at 31.7 percent, dipped to 26.2 percent in urban non-slum areas, and was lowest in rural areas at 19.1 percent. The latest serosurvey also separately sampled healthcare workers and those who work in hospital settings. It was found that nearly 26 percent of doctors and nurses have coronavirus antibodies, as did 25.4 percent of paramedical staff pointing to the higher exposure to coronavirus infections than the general population. A scientific review of the second nationwide serosurvey by the Lancet can be accessed here. A similar review of the third survey has not been carried out yet.
Recent serosurveys in Delhi, Pune and Hyderabad all show high prevalence in urban settings. The fifth round of the serological survey conducted in Delhi between January 15 and 23 among 28,000 people reported an antibody prevalence of 56.13 percent. A study in Karnataka between June-August 2020 reported a statewide prevalence of 46.7 percent, while another survey conducted in September 2020 showed a prevalence of 27.3 percent.
However, based on all surveys done so far, there seems to be no region in the country that can be deemed to have attained herd immunity, even as some urban pockets may have crossed a 60 percent positivity rate by now. In an interview, Dr. K. Srinath Reddy, President of the Public Health Foundation of India said that is not correct to characterise India as a homogenous country that simultaneously attains herd immunity all across its vast geography and huge population and that differences between urban and rural areas, slums and non-slums, well developed districts and less developed districts, which lead to different levels of exposure to the virus, need to be accounted for.
Director of the All India Institute of Medical Sciences Dr RandeepGuleria was quoted in an interview saying that a large number of people have already been infected in the crowded cities, where the virus was spreading a lot and have gained some kind of immunity. “This basically means that there has been a break in the chain of the transmission and the virus is not spreading from one person to another at a very fast rate, at least in some bigger areas or cities, which were badly infected earlier. Crowded areas of Delhi, Mumbai and urban slums fall in this category. In rural areas there is still a lot of susceptible population, but they are scattered and therefore the chances of the virus spreading rapidly is less.’
However, as per a report, a senior epidemiologist involved in the survey said that infection rates in rural areas are catching up too. “The spread is certainly slower in rural areas because of density but that doesn’t mean we are immune from future spikes and it would be wise to probably prioritise vaccination in the villages than cities. The survey also doesn’t account for the possibility of reinfection, or whether we will be more vulnerable to mutant strains.”
Vaccination Update:
Twenty six days since the government started the pan-India vaccination drive on January 16, it has managed to vaccinatemore than seven million people. The Union Ministry said in a statement on February 11 that India has become the fastest country in the world to achieve over seven million vaccinations. It took 27 days for the United States and 48 days for the United Kingdom (UK) to reach the same figures. The statement also said that at least 50 percent of accredited social health activists (ASHA), has also been vaccinated as of Wednesday, February 10.
India began the Covid-19 immunisation drive with two locally manufactured vaccines, Covishield developed by Oxford University-AstraZeneca and made by Serum Institute of India (SII), Pune, and Covaxin, developed and produced by Bharat Biotech International. It immediately started administering the jabs to healthcare workers in the first phase. The government estimates that close to 10 million healthcare workers are registered to receive the vaccine against Covid-19.The vaccination drive is now set to be ramped up, targeting a larger population group of around 260 million people above the age of 50. This is likely to begin in a phased manner from March 1.
Other Contenders:
A slew of other promising vaccines are in different stages of clinical trials and are likely to secure emergency use authorization over the next few months. This is set to increase the availability of vaccines in India.
A joint note from the Indian Council of Medical Research and the Serum Institute of India stated that the two had collaborated for the clinical development of Covovax, developed by American company Novavax and upscaled by the SII.The SII has applied to the Indian authorities to conduct a small domestic trial of Novavax’s coronavirus vaccine. The firm is hopeful of launching the Covid-19 vaccine by June this year, under the local brand Covovax.Novavax’s coronavirus vaccine was found to be 89.3 percent effective in a UK trial and was nearly as effective in protecting against the more highly contagious variant first discovered in Britain.
Hyderabad-based Biological E is looking at contract-manufacturing the Johnson & Johnson Covid vaccine. In August, Biological E had entered into an agreement with one of the Janssen Pharmaceutical companies of Johnson & Johnson, for the manufacturing of the Johnson & Johnson’s COVID-19 vaccine. Biological E is also looking at producing its own Covid vaccine this year. Biological E’s own covid vaccine is under clinical trials and interim data is expected this quarter. Apart from these, the regulator is expected to approve Russia’s Sputnik V and Cadila Healthcare’s ZyCov-D vaccines in the next few months.
In addition to its vaccination drive in India, indigenously manufactured vaccines are also being exported to over ten countries. India is working on plans to scale up vaccine manufacture to supply to as many as 60 nations in the coming months.
As per reports, India has supplied over 15 million doses of the Oxford-AstraZeneca vaccine manufactured by the SII to 20 countries. This includes nearly 6.3 million doses supplied free to countries such as Bangladesh, Myanmar, Bhutan, Nepal, Afghanistan, Sri Lanka, Bahrain and Oman, Barbados and Dominica. About 10 million more doses were supplied on a commercial basis to seven countries including Brazil, Morocco and South Africa. Bharat Biotech is also likely to start exports to countries like Brazil and the United Arab Emirates by the end of this week.
Variants Update
Multiple SARS-CoV-2 variants are circulating globally. Several new variants emerged in the fall of 2020. The latest list can be accessed here, on the website of US Government’s Centre for Disease Control. Of all, three COVID variants, in particular, carry the most risks- ones which have emerged from Kent, UK ( B.1.1.7 variant), South Africa (B.1.351 variant) and Brazil (B.1.1.28.1 or P.1 variant).
Last week, scientists at India’s CSIR-Centre for Cellular and Molecular Biology here have found a different variant of SARS-CoV-2 in southern parts of India. The different variant appears to be milder than the existing one and the institute is stepping up research on it to ascertain its prevalence in the country. The variant is seen in Telangana and Andhra Pradesh and other southern states and scientists have no sufficient data to prove its existence in other parts of the country.
Despite the national downward trend in cases, the continued transmission in Kerala and Maharashtra has evoked the possibility of an undetected mutant strain of Sars-CoV-2 circulating in the two states. Data of the past one week showed that both the states account for 71 per cent of the fresh caseload of the week with Kerala making up almost half of the total.
In light of these mutations, it is believed that the composition of the Covishield vaccine may have to be altered, after the World Health Organization’s (WHO) Strategic Advisory Group of Experts on Immunization (SAGE) expressed concerns over the effectiveness of the vaccine against the South African mutant coronavirus strain. Bharat Biotech has stated that Covaxin shows promising results against the variant. But since data on the last phase of its clinical trials and early stages of mass vaccination is awaited, the certainty of these claims cannot be verified.
At the global level, according to the CDC guidelines, most vaccines right now will be able to suffice ample protection against the different variants of COVID-19. But this piece of information is still being researched, and since it’s a relatively new virus, there is no proof yet to prove the claim right.
In Conclusion
Even after over a year of the pandemic, the world still does not have a full explanation for all the different trends being observed across countries and regions. The pandemic is likely to continue to decline in India and herd immunity will eventually be achieved from a combination of vaccination and natural infection. In the meanwhile, we should not become complacent and not and let our guard down till countrywide herd immunity becomes a reality.
References:
https://www.thelancet.com/action/showPdf?pii=S2214-109X%2820%2930544-1