With the number of novel coronavirus cases reported so far continuing to rise in most States even during the national lockdown that came into force since March 25, India faces the great challenge of containing its spread just days before the May 3 deadline for lifting the lockout. With the number of cases increasing from 519 on March 24 to nearly 28,000 on April 27, the lockdown has indeed prevented an explosion of cases.
As the World Health Organisation (WHO) had pointed out on March 25, the unprecedented measures of the shutdown can only buy time and reduce the pressure on the health-care system. But by itself, it cannot “extinguish epidemics”.
Contrary to WHO’s advice of using the opportunity to carry out more precise and targeted measures to chase and contain the virus, there have been no concerted efforts to aggressively test and isolate positive cases even in hotspot and containment areas.
In light of this, will extending the lockdown become a default option as was done after the first phase of restriction ended on April 14 even as the government believes there is no community transmission yet in India? Or, as many experts have been advocating, will India bite the bullet and opt for lifting the restrictions in a phased manner?
Weighing in
Dr. Giridhar R. Babu, an epidemiologist at the Public Health Foundation of India, Bengaluru and a member of the COVID-19 task force of Karnataka and Dr. Jayaprakash Muliyil formerly with the Christian Medical College, Vellore, say that without doubt there will be an increase in the number of cases once the lockdown is lifted; particularly so as no effort was made to hunt the virus during the lockdown period. But a careful, graded approach to lift the restrictions can still help prevent a huge spike in cases and create a concomitant strain on the healthcare system.
Any strategy adopted for lifting restrictions should bear in mind that the actual number of people who have been infected is many times more than the laboratory-confirmed cases. Dr. Babu estimates the total number of infections to be around 2,50,000 while Prof. Muliyil says that for every recorded case, there are 60 people who have not been counted.
While extending the lockdown in hotspot areas appears not only prudent but also essential, there should be more focus during the remaining days of the lockdown on silent areas that have not reported any case or just a few cases. Increased surveillance of those exhibiting severe acute respiratory infection (SARI), influenza-like illness (ILI) and any COVID-19 suspect cases in the silent areas will help determine if restrictions should be eased or continued after May 3. Sikkim, which has walled itself up has not reported a single case; some northeast States have reported only a few cases. These States would not need a continued lockdown, once the true infection prevalence is ascertained. Most importantly, the decision on whether to continue the restrictions or not should be taken at the local level; a centralised approach to decision making will be hugely counterproductive.
As Dr. Babu strongly advocates, it is important to segregate essential and non-essential activities and encourage more people to work from home till such time as an effective vaccine or anti-viral becomes available. Universal mask wearing, physical distancing and observing hand hygiene will help in curtailing the spread; but these will not be practical in slums and other crowded neighbourhoods.
On herd immunity
This brings to the fore a more natural way to slow down and bring the epidemic to an end through herd immunity that happens naturally during an epidemic. Herd immunity arises when a sizeable population gets naturally infected over a period of time so that the virus does not easily find a susceptible host to infect, thus bringing the epidemic to a halt — this is what Dr. Muliyil and virologist Dr. T. Jacob John advocate.
The herd immunity that these scientists are referring to is not very dissimilar from the one practised by British Prime Minister Boris Johnson who intended using it as a strategy to end the epidemic. But the difference is that while Mr. Johnson put even the elderly and those with comorbidities at risk of infection through his approach, both these scientists have kept the interests of the elderly and those with comorbidities as top priorities. While these two categories of people who may experience serious symptoms and even death can protect themselves by self-isolation — also called as reverse quarantine — the young, who mostly exhibit only mild symptoms, can go out by following containment measures together with universal mask wearing, physical distancing and hand hygiene.
Strictly following containment measures, wearing a mask and maintaining physical distancing not only slow down the rate of infection but also the rate at which herd immunity is achieved naturally. But that is a small price to pay in order to avoid overwhelming the health-care system, if many require hospitalisation.
In the case of H1N1, in 2009, the swine flu pandemic died out in two years when 40% of the population where the virus was spreading had been naturally infected. But it comes back each year as the susceptible population through new birth grows beyond the threshold. The same was true for all the previous influenza pandemics — the 1918 Spanish flu, 1957 Asian flu, and 1968 Hong Kong influenza. Even during the pre-vaccination days, measles used to strike once in three years and German measles every seven years. Dr. Jacob John expects at least one year for herd immunity to develop naturally for the novel coronavirus, provided shutdowns are eased.
Though other strains of coronavirus, which cause the common cold, infect people almost every winter, the same strain does not infect people twice. But the mutations that these viruses undergo make most people susceptible to infection. Fortunately, the novel coronavirus appears more stable (experiences fewer mutations) than other influenza viruses and so an infected person may probably be protected against future disease, Dr. Muliyil hopes.
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WHO cautions that “there is currently no evidence that people who have recovered from COVID-19 and have antibodies are protected from a second infection”. Infected people may have some level of protection against the virus, but the level and duration of protection is still unknown. In South Korea, at least 222 people who have recovered from the disease have again tested positive. It is still not clear if it is a case of reinfection or reactivation (where infected people have not been able to completely clear the virus).
prasad.ravindranath@thehindu.co.in