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 Table of Contents  
PERSPECTIVE
Year : 2021  |  Volume : 23  |  Issue : 2  |  Page : 205-207

Future of the coronavirus disease-2019 pandemic: An evidence-based insight


1 Capt (MS) Health, IHQ of MoD (N), New Delhi, India
2 ADGMS (N), IHQ of MoD (N), New Delhi, India
3 DGMS (N), IHQ of MoD (N), New Delhi, India
4 PhD Scholar, AIIMS, New Delhi, India
5 Cdr (MS) MH&S, IHQ of MoD (N), New Delhi, India
6 Cmde (MS) – HS, IHQ of MoD (N), New Delhi, India

Date of Submission23-Sep-2021
Date of Decision24-Sep-2021
Date of Acceptance25-Sep-2021
Date of Web Publication18-Oct-2021

Correspondence Address:
Surg Capt Sougat Ray
Capt (MS) Health, IHQ of MoD (N), New Delhi
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jmms.jmms_122_21

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How to cite this article:
Ray S, Naidu C S, Maramraj KK, Chawla N, Vashisht S, Roy K, Gopinath A. Future of the coronavirus disease-2019 pandemic: An evidence-based insight. J Mar Med Soc 2021;23:205-7

How to cite this URL:
Ray S, Naidu C S, Maramraj KK, Chawla N, Vashisht S, Roy K, Gopinath A. Future of the coronavirus disease-2019 pandemic: An evidence-based insight. J Mar Med Soc [serial online] 2021 [cited 2021 Dec 9];23:205-7. Available from: https://www.marinemedicalsociety.in/text.asp?2021/23/2/205/328435



Whether the coronavirus disease-2019 (COVID-19) pandemic will be declared “over” by the WHO by end of the year or late next year or 2 or 3 years down the line is anybody's guess. Mathematical predictive models have continued to fail miserably. Lockdowns and unpopular restrictions across the globe have not really helped as cases have emerged among those who remained susceptible.

In India, the initial thought of ending the COVID-19 pandemic by May 2020 due to the dramatic and brutal lockdown of Mar 23, 2020 and the heat generated by the summer was shattered with massive number of cases in the 1st wave. The 1st wave petered out mysteriously and by Diwali festival in October 2020, people started thinking that COVID is a thing of the past. The reason was attributed to the development of herd immunity primarily due to results of 1st and 2nd national serosurveys (August 2020) which found one in 15 Indians had COVID-19 infection.[1] Just when we had let our guard down, the devastating second wave stuck heavily in the month of February to May 2021 killing lakhs of people.

In the beginning of 2021, however, the game was changing. Vaccines were approved, and the world was vaccinating adults. Although vaccination has been found to be effective in protecting individuals from falling ill and dying, breakthrough infections have been rampant. It also appeared that people could pass on the infection to others, despite being vaccinated. This article aims to update our perspectives on when the coronavirus pandemic will end, if at all, and to reflect the latest information on variants of concern and impact of vaccination.


  The Delta Variant Top


The severe acute respiratory syndrome coronavirus 2 (SARS CoV 2) B.1.617 lineage including the delta (B.1.617.2) is believed to have originated from Maharashtra, India in December 2020 and designated to be a Variant of Concern on May 11, 2021 by WHO.[2] There is thus a possibility that the second wave (March 2020 to June 2020) in India occurred predominantly due to the delta variant, which has now circulated to other countries across the globe. The delta variant is 60% more transmissible than the alpha variant (B.1.1.7) and twice as than the original Wuhan virus.[3] Recent studies have also noted that delta strains collected from samples from infected and vaccinated persons showed less neutralizing activity than the original Wuhan virus.[4] In fact, the Delta variant has effectively moved overall herd immunity out of reach in most countries for the time being.


  Variants of Concern – Why did they Emerge? Top


Signs of reversal of trend of infection across the world have been marred by emergence of variants. Cases caused by the Delta variant reversed the transition toward normalcy first in the United Kingdom, during June and July of 2021 and subsequently in other nations. The more opportunities a virus gets to spread to different geographical regions, the more it mutates. It is neither new nor unexpected. The first COVID variant was the alpha variant, noted in the UK. Several other variants have emerged later. Usually, viral mutants have lesser impact on the ability to become more contagious. However, this time around, the changes of mutation have taken place differently, and the variants have become more transmissible than the original virus. Exact cause of this increased transmissibility has remained mostly unknown. Some studies have brought out that this occurred due to alteration of the host immune profile of the general population.[5] Other studies have found probable causes to be development of escape mutations of the spike protein exerted by convalescent plasma and monoclonal antibody treatments, though some studies have refuted this claim.

Newer variants might continue to emerge and possibly will be the sole criteria driving the pandemic in terms of infectivity, transmissibility, virulence, antigenicity, and antibody recognition.[5]


  Will Vaccine Mediated Immunity Wane with Time? Do we Need a Booster? Top


Levels of neutralizing humoral antibodies are commonly assessed, post vaccination and for individuals with past COVID infection, as a surrogate marker of a protective COVID state. Waning of the neutralizing antibodies in recent studies has, however, raised doubts over the vaccine efficacy and need for a booster dose. A recent study from Israel found that, in vaccinated and convalescent subjects (mRNA-Pfizer), antibody titers decreased with time. They found that 16% of the vaccinated subjects (mean age of 56.45 years) and 10.8% of those who were previously infected (mean age of 41.99 years) had antibody levels below the seropositivity threshold of <50 AU/mL. The antibody titers decreased faster in older age group and those with diseases such as diabetes and malignancy. The decrease in the titer was slow in case of symptomatic COVID patients.[6] In another study published recently in Lancet, the authors are of the view that reductions in neutralizing antibody titer do not necessarily predict reductions in vaccine efficacy over time as a COVID protective state against severe disease is mediated not only by antibody responses, which is short lived after vaccine administration or after infection, but also by memory responses and cell-mediated immunity. The effectiveness of the current vaccines in vogue has also been found to be substantially high, especially in preventing severe disease, caused by variants including the delta variant. They have also noted that the present vaccines, which have been developed from the original virus antigen, have elicited immune responses against the currently circulating variants and have prevented individuals from severity of the disease. This indicates that the variants might have not yet evolved to a point at which they are likely to escape the memory immune responses induced by these vaccines.[7],[8]

The available evidence to decide on recommending a booster dose, therefore, might not be adequate at this moment. At presently, however, whether booster should be administered to individuals who are at risk, including Health Care Workers, Front Line Workers, old people and the immunocompromised, without completing primary immunization of deprived population, is debatable. There is a definite need for more controlled studies on boosters for the currently available vaccines and development of new variant-based vaccines before there is widespread need for them.

The DNA-based vaccine, ZyCoV-D recently approved in India, offers promise. Not only that it confers long-lasting immunity, but that the vaccine was developed when the delta variant was the dominant one in India, whereas all other vaccines were developed during the original Wuhan variant. An intranasal vaccine also offers hope. It stimulates a broad immune response – neutralizing IgG, mucosal IgA, and T-cell responses at the site of infection (in the nasal mucosa) – essential for blocking both infection and transmission of COVID-19. The nasal route has excellent potential for vaccination due to the organized immune systems of the nasal mucosa.[9] There are concerns too-an over-activation of the immune system due to development of subneutralizing antibodies might lead to exacerbation of the infection, known as Antibody Dependent Enhancement.[10]


  Should Life Open up Now? Top


It is now amply clear that there might not be any epidemiological end point to COVID-19. The disease eventually might become endemic. This will be due to development of herd immunity with decreased R nought, where an infected person will not be able to transmit the disease to more than one person due to reduced susceptible individuals. Pandemics have a natural tendency to get transformed into an endemic when enough people gain immune protection. The end to the emergency part of the pandemic would mean reduced hospitalizations and deaths from COVID-19. Countries like UK are relaxing public health measures as they perceive that the delta wave is well under controlled with less people dying. This transformation to endemicity will invariably depend on emergence of lethal newer variants of the original SARS-CoV-2 virus. Endemicity seems to be a more realistic future of the disease than herd immunity.[11] The disease can evolve to be like a flu like illness, where descendants of SARS-CoV-2 circulate all over the globe, and only to turn into a lethal epidemic in a naive population. Or else, the disease can transform to a measles-like illness where the prevalent vaccines prove to be highly effective against future variants, and the disease is effectively controlled in places where people have been vaccinated completely.[12]


  Conclusion Top


New cases and deaths have been falling in most part of the world. Newer therapeutics have received Emergency Usage Authorisation which has the potential to reduce hospitalizations. It is becoming more and more clear that a lethal newer variant can only drive a new wave in future, otherwise the disease is likely to develop into an endemic one with sporadic outbreaks. Vaccination needs to be accessible and acceptable to all.

The dilemma among the population is visibly evident. On one hand, there is a risk of being trapped in a seemingly never-ending cycle of lockdowns and travel-related quarantine, and on the other hand, there is a risk that the disease might affect the susceptible groups, which include children. The only glimmer of good hope is that the risk of dying of COVID is falling due to extensive vaccination. Current vaccines have shown good effectiveness in preventing severity and deaths against delta variant. The pandemic, however, will possibly be controlled only when emerging virus variants do not transmit as fast, are less lethal, and cannot avoid the immune environment thus created so far.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Murhekar MV, Bhatnagar T, Selvaraju S, Saravanakumar V, Thangaraj JW, Shah N, et al. SARS-CoV-2 antibody seroprevalence in India, August-September, 2020: Findings from the second nationwide household serosurvey. Lancet Glob Health 2021;9:e257-66.  Back to cited text no. 1
    
2.
Tracking SARS CoV Variants. Available from: https://www.who.int/en/activities/tracking-SARS-CoV-2-variants/. [Last accessed on 2021 Sep 20]  Back to cited text no. 2
    
3.
Edara VV, Pinsky BA, Suthar MS, Lai L, Davis-Gardner ME, Floyd K, et al. Infection and vaccine-induced neutralizing-antibody responses to the SARS-CoV-2 B.1.617 variants. New Eng J Med 2021;385:664-6.  Back to cited text no. 3
    
4.
How Dangerous is the Delta Variant? Available from: https://asm.org/Articles/2021/July/How-Dangerous-is-the-Delta-Variant-B-1-617-2. [Last accessed on 2021 Sep 20].  Back to cited text no. 4
    
5.
Harvey WT, Carabelli AM, Jackson B, Gupta RK, Thomson EC, Harrison EM, et al. SARS-CoV-2 variants, spike mutations and immune escape. Nat Rev Microbiol 2021;19:409-24.  Back to cited text no. 5
    
6.
Israel A, Shenhar Y, Green I, Merzon E, Golan-Cohen A, Schäffer AA, et al. Large-scale study of antibody titer decay following BNT162b2 mRNA vaccine or SARS-CoV-2 infection. medRxiv 2021;[Preprint] [doi: 2021.08.19.21262111].  Back to cited text no. 6
    
7.
Krause PR, Fleming TR, Peto R, Longini IM, Figueroa JP, Sterne JAC, et al. Considerations in boosting COVID-19 vaccine immune responses. Lancet 2021;:S0140-6736(21)02046-8.  Back to cited text no. 7
    
8.
9.
Malapatty S. India's DNA COVID vaccine is a World's first – More are coming? Nature 2021:597:161-2.  Back to cited text no. 9
    
10.
Intranasal Vaccine For Covid-19 | Bharat Biotech. Available from: www.bharatbiotech.com/intranasal-vaccine.html. [Last accessed on 2021 Sep 20].  Back to cited text no. 10
    
11.
Ricke DO. Two Different Antibody-Dependent Enhancement (ADE) Risks for SARS-CoV-2 Antibodies. Front Immunol 2021;12:640093.  Back to cited text no. 11
    
12.




 

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The Delta Variant
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Should Life Open...
Conclusion
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