Connecting The Dots To Mitigate A Third Wave

Context: DOTS framework helps in understanding the dynamics of the second wave of the Covid pandemic and thereby helps in mitigating the third wave.

About DOTS framework: And its relationship with Reproduction Number – R -

• Reproduction number – R: It denotes the average number of new infections arising from one infected individual. R fluctuates overtime during an epidemic.
  • When R is greater than 1, infected individuals infect more than one person on average, and we observe increasing cases.
• Determinants of R – DOTS: Each of the following factors is required for increasing cases; reducing any of them to 0 would extinguish an epidemic.
  • D – Duration a person is infectious.
  • O – Opportunities infected individuals have to spread the infection to others.
  • T – Probability Transmission occurs given an opportunity.
  • S – Average Susceptibility of a population or subpopulation.

DOTS’ analysis of the second wave: Factors that led to the second wave of Covid pandemic -

• D: There are evidence of rise in duration due to new variants.
• O: Reduced social distancing and other precautionary measures, thereby increasing the opportunities for transmission. Superspreading characteristic of COVID-19 also contributed:
  • Research from Tamil Nadu and Andhra Pradesh shows that only 5% of infected individuals accounted for roughly 80% of all secondary infections.
• T: New variants that are more transmissible have emerged. E.g. B.1.617.2 or the delta variant is potentially twice as much transmissible as those circulating in 2020.
• S: Results from the national seroprevalence survey done in December 2020 and January 2021 indicate that roughly 25% of the population had antibodies. By end-March, less than 1% of the total population had received two doses of vaccine. Both indicate huge susceptible population

Way forward: Mitigating a potential third wave

• Need well-designed seroprevalence surveys: To understand how much population remains susceptible and where they reside.
  • Take into account new complications: Like the waning immunity and potential for reinfections, rise of new variants etc., which increases susceptibility.
• Drive down the factors that contribute to R:
  • Temporary solutions like lockdowns should be used to focus on slowing transmission.
  • Substantially increase immunisation coverage: Currently, only 3% population received both doses.
  • Behavioural interventions: Like increased use of face masks and improved ventilation.
    • Research from Bangladesh indicates that providing free masks together with community monitors can help improve adoption.
    • Considering the threat of new variants, isolation and quarantining guidelines should be revisited to minimise potential exposure to others.