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 Table of Contents  
Year : 2021  |  Volume : 11  |  Issue : 4  |  Page : 163-166

Saga of COVID-19: Focus on third and subsequent waves

1 National Health Systems Resource Centre, New Delhi, India
2 Department of Community Medicine, Armed Forces Medical College, Pune, Maharashtra, India

Date of Submission22-Jul-2021
Date of Decision26-Jul-2021
Date of Acceptance26-Jul-2021
Date of Web Publication21-Aug-2021

Correspondence Address:
Dr. Atul Kotwal
National Health Systems Resource Centre, New Delhi - 110 067
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/cmrp.cmrp_72_21

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How to cite this article:
Kotwal A, Yadav AK, Pareek A. Saga of COVID-19: Focus on third and subsequent waves. Curr Med Res Pract 2021;11:163-6

How to cite this URL:
Kotwal A, Yadav AK, Pareek A. Saga of COVID-19: Focus on third and subsequent waves. Curr Med Res Pract [serial online] 2021 [cited 2022 Aug 12];11:163-6. Available from: http://www.cmrpjournal.org/text.asp?2021/11/4/163/324256

  Introduction Top

The first case of COVID-19 was reported to the World Health Organisation (WHO) on 31st December 2019. By 11th March 2020, when the WHO declared it as a pandemic, it had already spread to 114 countries and six continents.[1] In India, the first case of COVID-19 was reported on 30th January 2020. Since then, cases increased to a peak of 97,860 on 16th September.[2] From December 2020 to February 2021, cases remained in control but started peaking again in March and reached peak of 414,280 fresh cases on 6th May 2021. At present, the daily new cases are hovering around 40,000 with states such as Kerala and Maharashtra reporting a greater number of cases. The number of cases and measures implemented are depicted in [Figure 1]. The ferocity of the second wave had taken everyone by surprise, especially proclamations by several policy-makers and researchers believing that India had attained herd immunity after the first wave and might just scrape through with minimal damage during the subsequent waves.[3]
Figure 1: Impact of stringency index on waves. Stringency index is a composite measure based on nine indicators including school closures, workplace closure and travel bans, rescaled to a value from 0 to 100 (100 = strictest)

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  The Past: Repeating Itself or Rhyming? Top

In Europe in 1918, influenza spread through Spain, France, Great Britain and Italy, causing havoc with military operations during the First World War. The influenza pandemic of 1918 killed more than 50 million people worldwide. There were four distinct waves as per the available data. The first large peak was in February 1918, second peak in October 1918, third wave in December 1918 followed by the fourth wave in February 1920. In India, Bombay (now Mumbai) was the first to witness the peak in 1918 and it is bearing the worst brunt of COVID-19 today. According to the study, India experienced two distinct epidemic waves: A mild one in the summer of 1918 and a far more severe one in autumn and winter. The death toll in India's British-ruled districts was 13.88 million. Identifying suspected cases through surveillance, and voluntary and/or mandatory quarantine or isolation, enabled the spread of Spanish flu to be curbed. At that time, these public health measures were the only effective weapons against the disease, as no vaccines or antivirals were available.[4]

  Second Wave in India Top

A large pool of susceptible population was present after the first wave. Local and state elections, large religious gatherings, unrestricted travel and not following COVID appropriate behaviour by majority of the population offered the virus a fast track to susceptible population. Variants arrived through travellers (B.1.1.7) or emerged in India (B.1.617 and B.1.618) to add speed and scale to the surge.[5] A second wave beginning in March 2021 was steeper than the first.[6] By late April, India led the world in new and active cases. On 30th April 2021, it became the first country to report over 400,000 new cases in a 24-h period.[7] The second wave placed severe strain on the health-care system, including a shortage of medical oxygen. As on 19th July 2021, there are 399,998 active cases, 414,513 total deaths, test positivity ratio 2.0% with case fatality ratio 1.3% in India.[2],[8]

  Experiences of Other Countries Top

There is no uniform pattern across the countries. While some countries clearly show multiple waves, several others still continue to have a high number of daily infections (e.g., Brazil and Colombia). In countries that show multiple waves (USA, UK and Turkey), the gap between peaks is also not uniform. This is understandable since local dynamics in each country differ and influence this pattern. The number of daily confirmed cases and waves are shown in [Figure 2].[9]
Figure 2: Daily new confirmed COVID-19 cases

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  Third and Subsequent Wave/S Top

India started its vaccination campaign from 16th January 2021 onward with two vaccines, namely the Oxford–AstraZeneca vaccine (AZD 1222), manufactured by the Serum Institute of India under the trade name “COVISHIELD”, and “COVAXIN” (BBV152), a vaccine developed by Bharat Biotech in association with the Indian Council of Medical Research and National Institute of Virology.[10]. As on 20th July 2021, in a remarkable achievement, India's vaccination drive has crossed 40 crore mark of administered doses, with 32.85 crore receiving first dose and 8.66 crore receiving two doses.[8] As on 20th July, the percentage of eligible population (>18 years) covered by single dose is 39.3% and double dose is 10.38%.[2] However, there is a wide inter-state variation in vaccination coverage, ranging from 15.5% (UP) to 71% (Sikkim).

Serosurveys also provide indication about the spread of infection in the society. The third pan India ICMR survey which was conducted between 18th December 2020 and 06th January 2021 in the general population in the age group of >10 years and HCW's, showed 24.1% and 25.6% adjusted seroprevalence, respectively. However, several cities and states have conducted their own serosurveys. Metropolitan cities such as Delhi, Mumbai, Pune, Chennai and Hyderabad have reported seroprevalence ranging between 17.6% and 56% at different time points.[11] The fourth round of national serosurvey that was conducted in 70 districts in June–July 2021 revealed that a third of the population did not have antibodies against the COVID-19 disease, meaning about 40 crore Indians were still vulnerable to the virus. Overall seroprevalence was 67.6% (95% confidence interval 66.4, 68.7) with an age gradient. The prevalence in the 6–9 age group being 57.2%, among 10–17 years olds 61.6%, 18–44 years, 66.7%, 45–60 years, 77.6% and 76.7% among more than 60 years age.[12]

It may thus be assumed that children might have been equally affected during the second wave. The data on infected cases from the MoHFW also showed no change of age profile in the first and second waves. In addition, there is no clear evidence on long-term immunity from vaccination or natural infection. The countries such as Israel are mulling third booster dose.[13] Thus, there is still susceptible population present albeit these susceptibles are spatially heterogeneously distributed not only at national level but also at the state and district level. This spatial heterogeneity calls for innovations at local levels to prevent spread of infection. Surveillance at local level and judicious use of vaccination for containment may yield better results from now onwards than the vaccination of complete population. Another important issue regarding vaccine is vaccine hesitancy due to which it may never be possible to have 100% coverage even if accessibility and affordability is assured.[14]

Besides the host susceptibility, any activity which increases contact among the people would likely increase the number of cases. Not following COVID appropriate behaviour such as social distancing and wearing appropriate mask may also lead to increase in cases.[15] A survey conducted by ICMR showed that only 50% of people have worn mask at the peak of the pandemic.[15] Another important preventive measure of ventilation in closed spaces needs enhanced community participation and stricter implementation.

As per recent genome sequencing, most prevalent variant in India is Delta variant (81%), followed by beta (4%) and Kappa (1.35%).[16] As per the report published by Indian SARS-CoV-2 Genomic Consortium Delta sub-lineages AY.1 and AY.2 are declining globally with near zero cases in the last week of June in either UK or US, where they were most frequently seen. They also continue to be below 1% in available sequences from June in India. It is likely that neither AY.1 nor AY.2 is more transmissible than Delta. There are no indications of rising trend in the four clusters (in Ratnagiri and Jalgaon in Maharashtra, Bhopal in MP and Chennai in TN). Meanwhile, AY.3 has been identified as a new Delta sub-lineage, defined by ORF1a: I3731V common AY.1 mutations except for S: K417. It is primarily seen in the US with single reclassified case in the UK and India. There are no known significant properties of this mutation. As the second wave is attributed to highly transmissible delta mutant and in future, there is a possibility of mutant becoming further transmissible or able to evade immune mechanism, hence increasing the proportion of samples for genomic surveillance is very important.

Reduction in the transmission of COVID-19 virus by COVID-19 appropriate behaviour and other NPIs and higher vaccination coverage will not only prevent the number of cases but also lessen the chances of random mutations by reducing virus circulation and multiplication. People in India need to be cautious, especially in the coming festival season of October to November. The current rate of re-infection is low; however, waning immunity after vaccination over a period of longer duration like 6 months and a year remains a matter of concern. The current data suggest probability of reinfection coupled with significant protection from severe disease, hospitalisation and mortality.[17]

Different mathematical models like the SUTRA model for COVID-19 pandemic predict a third wave to occur between October and November. Another model has predicted the third wave as early as August this year.[18] However, none of the models suggests that the third wave would be more devastating than the second wave. In the most pessimistic scenario, the third wave would be comparable to the first one.[19] However, regional/local modelling will be more helpful in predictions as compared to the country wide models ignoring the heterogeneity.[20] Mathematical modelling also suggests that disease with asymptomatic transmission would become endemic rather than complete elimination.

  Conclusion Top

At present, India is reporting around 40,000 new cases per day for over the past 16 weeks, with very few states showing high positivity rate.[2] Vaccination coverage is increasing, and also repeated serosurveys have confirmed increasing percentage of population being detected with antibodies. Even then, the susceptible population in India is huge with spatial heterogeneity. Robust local surveillance and containment by the judicious use of vaccine are way forward to prevent the spread of virus in the pockets of susceptible population. It is likely that in future there would be multiple ripples (largely small) in the ongoing saga of COVID-19. Test, track, treat, vaccinate, non-pharmacological interventions (COVID appropriate behaviour and ventilation) and surveillance are the keys to ride out this storm and come out stronger.

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Conflicts of interest

There are no conflicts of interest.

  References Top

WHO Director-General's Opening Remarks at the Media Briefing on COVID-19 - 2020 March 11. Available from: https://www.who.int/director-general/speeches/detail/who-director-general-s-opening-remarks-at-the-media-briefing-on-covid-19---11-March-2020. [Last accessed on 2021 Jul 20].  Back to cited text no. 1
Coronavirus Outbreak in India - Covid19India.org. Available from: https://www.covid19india.org/state/TT. [Last accessed on 2021 Jul 20].  Back to cited text no. 2
Reddy KS. Pandemic lessons from India. BMJ 2021;373:n1196.  Back to cited text no. 3
Martini M, Gazzaniga V, Bragazzi NL, Barberis I. The Spanish Influenza Pandemic: A lesson from history 100 years after 1918. J Prev Med Hyg 2019;60:E64-7.  Back to cited text no. 4
B.1.117 to B.1.618, India Has Many Covid Variants Causing Infections. Here are the Dominant Ones. Available from: https://theprint.in/health/b-1-117-to-b-1-618-india-has-many-covid-variants-causing-infections-here-are-the-dominant-ones/644693. [Last accessed on 2021 Jul 20], [Last accessed on 2021 July 15].  Back to cited text no. 5
India's Shocking surge in Covid cases follows baffling decline | India | The Guardian. Available from: https://www.theguardian.com/world/2021/apr/21/india-shocking-surge-in-covid-cases-follows-baffling-decline. [Last accessed on 2021 Jul 20], [Last accessed on 2021 Jul 18], [Last accessed on 2021 Jul 15].  Back to cited text no. 6
Coronavirus | India Becomes First Country in the World to Report Over 4 Lakh New Cases on April 30, 2021 - The Hindu. Available from: https://www.thehindu.com/news/national/coronavirus-india-becomes-first-country-in-the-world-to-report-over-400000-new-cases-on-april-30-2021/article34453081.ece. [Last accessed on 2021 Jul 15], [Last accessed on 2021 Jul 16].  Back to cited text no. 7
PIB. Available from: https://pib.gov.in/newsite/bulletinn.aspx. [Last accessed on 2021 Jul 17], [Last accessed on 2021 Jul 15].  Back to cited text no. 8
Ritchie H, Ortiz-Ospina E, Beltekian D, Mathieu E, Hasell J, Macdonald B, et al. Coronavirus Pandemic (COVID-19). Our World in Data. 2020 March 05. Available from: https://ourworldindata.org/coronavirus. [Last accessed on 2021 Jul 20].  Back to cited text no. 9
Expert Panel Clears Bharat Biotech's Covaxin Amid UK Virus Strain: What You Need to Know. Available from: https://www.news18.com/news/india/expert-panel-clears-bharat-biotechs-covaxin-amid-uk-virus-strain-what-you-need-to-know-3240500.html. [Last accessed on 2021 Jul 16] [Last accessed on 2021 Jul 15].  Back to cited text no. 10
Murhekar MV, Bhatnagar T, Thangaraj JW, Saravanakumar V, Kumar MS, Selvaraju S, et al. SARS-CoV-2 seroprevalence among the general population and healthcare workers in India, December 2020-January 2021. Int J Infect Dis 2021;108:145-55.  Back to cited text no. 11
Fourth Serosurvey Finds 67.6% Have Antibodies, 40 Crore Indians Still Vulnerable | Latest News India - Hindustan Times. Available from: https://www.hindustantimes.com/india-news/40-cr-indians-don-t-have-covid-anti-bodies-vulnerable-reveals-4th-serosurvey-101626779228818.html [Last accessed on 2021 Jul 20].  Back to cited text no. 12
Israel is Administering COVID Booster Shots. Who Qualifies to Get One? - The Jerusalem Post. Available from: https://www.jpost.com/israel-news/israel-is-administering-covid-booster-shots-who-qualifies-to-get-one-674250. [Last accessed on 2021 Jul 20].  Back to cited text no. 13
Dror AA, Eisenbach N, Taiber S, Morozov NG, Mizrachi M, Zigron A, et al. Vaccine hesitancy: The next challenge in the fight against COVID-19. Eur J Epidemiol 2020;35:775-9.  Back to cited text no. 14
50% of Indians don't Wear a Mask, Only 7% Wear it Correctly: Ministry of Health. WION. Available from: https://www.wionews.com/india-news/50-of-indians-dont-wear-a-mask-only-7-wear-it-correctly-ministry-of-health-386389. [Last accessed on 2021 Jul 22].  Back to cited text no. 15
Ritchie H, Ortiz-Ospina E, Beltekian D, Mathieu E, Hasell J, Macdonald B, et al. Coronavirus Pandemic (COVID-19). Our World in Data. 2020 March 05. Available from: https://ourworldindata.org/coronavirus. [Last accessed on 2021 Jul 15].  Back to cited text no. 16
CEDA || Will India face a third wave of Covid-19? Available from: https://ceda.ashoka.edu.in/will-india-face-a-third-wave-of-covid-19/. [Last accessed on 2021 Jul 15].  Back to cited text no. 17
Mandal S, Arinaminpathy N, Bhargava B, Panda S. Plausibility of a third wave of COVID-19 in India: A mathematical modelling based analysis. Indian J Med Res 2021; [Ahead of Print]. Available from: http://www.ijmr.org.in/. [Last accessed on 2021 Jul 20].  Back to cited text no. 18
Explained: SUTRA Model's Third Wave Predictions – How, When, What. Available from: https://swarajyamag.com/news-brief/explained-sutra-models-third-wave-predictions-how-when-what. [Last accessed on 2021 Jul 15].  Back to cited text no. 19
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