How to Stay Healthy and Hold Social Events Amidst Omicron Scare?

CME INDIA Presentation by Dr. Rajeev Jayadevan, MD, DNB, MRCP, ABIM (Med) ABIM (Gastro), NY. Vice Chairman, Kerala state IMA Research Cell. Member, National IMA Task Force on Corona Epidemic, Cochin.

Alpha, Beta, Delta or Omicron – Immunity is the King

“COVID-19 can be your best friend by giving you immunity, or your worst enemy by destroying your health and possibly killing you.” – Steven Magee

• Natural infection provides 90% protection. New study –(NEJM November 24)
• Analysis of reinfections showed 90% lower chance of severe disease compared to 1st infection, in age-matched controls.
• Reinfections were rare (Reinfection was defined as the first PCR positive swab obtained at least 90 days after the primary infection).

• Gap between 1st infection and reinfection was 9 months (IQR 179-315 days).
• No deaths or ICU admissions among all the reinfections studied in Qatar.
• Note: The age group along reinfections was relatively younger; only 5% in either group (reinfection or primary infection) were >50.
• Authors report from their previous study: “For a person who has already had a primary infection, the risk of having a severe reinfection is only approximately 1% of the risk of a previously uninfected person having a severe primary infection”(2)

Severity of SARS-CoV-2 Reinfections as Compared with Primary Infections in the Population of Qatar

Now Omicron Scare is palpable in India as cases get detected. Lots of social events are in succession. New Lancet paper from Paris, November 26 paves the way:

• A large indoor event can be safely held if:
  • Masks are worn
  • Antigen tests are done prior
  • Crowd is well-behaved
  • Indoor space is well-ventilated and not overcrowded (large space, few people. Only 20% of capacity was filled during concert).

• This was a large randomized study of 6678 people at Accor arena, Paris.
• The study compared two groups of people – 4451* attended the live concert, 2227 did not attend [*43% had vaccine. Pandemic was in the downward phase in Paris at that time].
• 7 days later, they were tested with rtPCR.
• The number of people who got infection was 0.2% and 0.15% in the two groups.
• (No difference whether they attended the concert or not).
• This shows that if conditions are met, large events can be safely held.

CME INDIA Learning Points

• Since February, 2020, the COVID-19 pandemic had put a stop to most major gatherings. After awaiting 3rd wave in India, physicians and public authorities became lax and COVID Appropriate behaviour (CAB) is not being followed for few months.
• Now Omicron Scare is around us and we need to follow CAB strictly.
• New Lancet study points that with physical distancing and masks, events can be organised  in enclosed environments.
• Previously one single randomised controlled trial, done during an indoor live concert in Barcelona in December, 2020, provided preliminary evidence that same day rapid antigen diagnostic testing and N95 mask use would prevent transmission.
• New – The SPRING (Study on Prevention of SARS-CoV-2 Transmission at a Large Indoor Gathering) is stated to be the first randomised, controlled trial which tested the hypothesis that systematic SARS-CoV-2 screening within the 3 days preceding the event and simple medical mask use by participants can prevent SARS-CoV-2 transmission for concerts held in enclosed spaces, at full capacity, with a standing audience.
• The trial has shown that participating in such an event was not associated with an increased risk of SARS-CoV-2 transmission.
• The results of the SPRING trial has shed light on the conditions required to resume live concerts and other indoor mass gatherings.
• “Until herd immunity is achieved and in a context of ongoing circulation of highly transmissible SARS-CoV-2 variants, resumption of cultural activities can be envisaged, provided a comprehensive preventive intervention, including testing within 3 days preceding the event and mask wearing, are implemented” (3) – This is the unique message.

CME INDIA Tail Piece

• Nice study. Transmission prevention is the effective tool to tamp down the spread of the virus. The rapid antigen test is best taken within 12 hours b4 the gathering. Its poor sensitivity (10,000 RNA copies/mL) means after 12 hrs viral load can reach 3e5/mL. – @jacquesenboit

References:

1. Lavine JS, Bjornstad ON, Antia R. Immunological characteristics govern the transition of COVID-19 to endemicity. Science 2021;371:741-5
2. Laith J. Abu-Raddad, Ph.D. Hiam Chemaitelly, M.Sc. Severity of SARS-CoV-2 Reinfections as Compared with Primary Infections.Correspondance/Nejm. November 24, 2021
   DOI: 10.1056/NEJMc2108120
3. Constance Delaugerre, Frantz Foissac, Hendy Abdoul. Prevention of SARS-CoV-2 transmission during a large, live, indoor gathering (SPRING): a non-inferiority, randomised, controlled trial. November 26, 2021 https://doi.org/10.1016/ S1473-3099(21)00673-3. www.thelancet.com

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