‘100% vaccine first dose coverage is pivotal moment for Mumbai’

For far-reaching health benefits, Mumbaiites must embrace masking, pay attention to indoor ventilation, and avoid crowds

Ever since the Covid-19 pandemic began, every step forward has felt like the quote from Lewis Carroll’s Through the Looking-Glass: “It takes all the running you can do, to keep in the same place”. While this tenacity has been important for us to avoid complacency, we shouldn’t deny ourselves a celebration of achievements along the way, and Saturday marks one such for Mumbai — 100% of the city’s target adult population has now received its first dose of the Covid vaccine.

BMC medical staff at KEM Hospital, Mumbai celebrate after giving the first vaccination shot on January 16, 2021, the first day of the national vaccination programme. (HT FILE)

Vaccinations achieve their intended goal when they prevent disease that warrants aggressive care. This is because the need for such care is commensurate with poor outcomes for patients as well as utilisation of resources in an overburdened healthcare system. We witnessed this during the first two waves in India, and all our efforts must be directed towards preventing this.

Thus, it is reassuring to know that even a single dose of the vaccine administered to a majority in India (Covishield) can provide up to 91% effectiveness against hospitalisations or death for the Delta variant, and reasonably high levels for other variants of concern (VOCs). It must be noted that these estimates tend to be lower for individuals above 60 years of age. The four-month data released by our health ministry in September suggests an overall protection of 96.6% against death with a single dose,indicating that a single dose of Covaxin, developed by Bharat Biotech and the Indian Council of Medical Research (ICMR), possibly does equally well at preventing death.

What about preventing symptomatic milder infection, and thus arresting transmission? This is where a single dose of the vaccine isn’t as impressive, and effectiveness tends to be between 30-70%, varying by study and type of variant causing these infections. This effectiveness increases significantly after two doses. It is heartening to know that 65% of the city’s target adult population have received two doses of the Covid vaccine, and we are hopefully on our way to achieving a 100% coverage with 2 doses.

What does this mean in the context of a possible third wave? Most experts agree that preventing it will depend on two factors: a) the evolution of newer variants of the virus which evade vaccine-induced and/or natural infection-conferred immunity and b) the incidence of breakthrough infections/reinfections with present variants.

The first factor is a serious concern, although it is reassuring to know that the effectiveness of the present vaccines against severe disease has remained high, irrespective of the VOC. Whether this continues to be the case might depend on our ability to keep transmission (and thereby, the evolution of newer variants) in check. This is where we cannot afford to let our guard down: getting the second doses administered as soon as possible, using effective vaccines for those below 18 years of age, and continuing to engage in behaviours that prevent transmission, are critical.

This is a pivotal moment in time when our embracing of masking, attention to indoor ventilation, and attitudes toward crowding might have far-reaching health benefits.

The second factor might need the administration of booster doses in the future, but this has to be weighed in the context of vaccine shortages across the globe. Although evidence clearly points toward increased breakthrough infections with the passage of time, such infections appear to be consistently of a milder nature, especially among the non-elderly and those who are not immuno-compromised.

The enthusiasm demonstrated by the city’s vaccination team, including frontline workers, administrators/planners in the Brihanmumbai Municipal Corporation (BMC) and allied teams, backed by the government, has resulted in this achievement for the city. As a proud Mumbaikar, I do hope that we sustain this momentum, and not only prevent the third wave, but work towards enhancing the overall health of the city.

(Dr Lancelot Pinto is a pulmonologist and epidemiologist at PD Hinduja Hospital)