COVID-19 has caused the world to slow down and, in many countries, completely shut down in a way not known in recent history. The impetus for the shutdown was driven in large part by a document from the Imperial College, London, which modelled options to handle the pandemic in high-income countries, specifically the U.K. and the U.S., which it called mitigation and suppression. Mitigation refers to methods to reduce the numbers infected and protect the most vulnerable. Measures advised are home isolation of suspect cases, home quarantine of those living in the same household as suspect cases, and physical distancing of those at most risk of severe disease. The measures described under suppression are more or less what have come to be called lockdowns but do not include complete shutdown of work. The aim of suppression is to prevent the infection from spreading to others. The authors said, in order to be effective, lockdowns needed to be in place for 12 to 18 months which is the time estimated for an effective vaccine to be available.
Waiting for herd immunity
The International Labour Organization reports that nearly 50% of the world’s labour force is in immediate danger of losing their livelihood. The Secretary-General of the UN, Antonio Guterres, says women are especially suffering the deadly impact of lockdowns. At a conservative estimate, for over 50% of the world’s population, a two-year lockdown would mean the end of their world.
Due to conflicting statements from the scientific community and governments, there is widespread fear that lifting the lockdown would mean disaster. Proponents of the concept of herd immunity have been criticised for being irresponsible. Herd immunity to a particular infection is a situation when so many in the population have immune antibodies that, although the pathogen is still in circulation, it can rarely find a susceptible host, and so illness from that pathogen is uncommon and cannot spread. For SARS-CoV-2, estimates are that 60%-70% of the population needs to have antibodies for the herd effect to occur. Critics point out that with the current estimate of 1% of the infected dying, waiting for herd immunity will still result in a lot of deaths. This argument ignores four factors: first, the number of deaths can be brought below 1% if we protect the most vulnerable, which is easier than locking down the entire population. Second, as statistics show, lockdowns also result in a very large number of deaths. Third, the pandemic will end much sooner than two years if herd immunity occurs. Fourth, we do not know the actual number infected up to now, as no country has reliable data. Therefore, a gradual exit, using mitigation measures, will save the greatest number of lives.
Critics also state that it is not certain if infection with this virus leads to immunity. This is based on the fact that a small number of people who tested positive were quarantined and allowed to leave quarantine after testing negative, only to test positive again later. There are other explanations for this phenomenon which are more robust than the ‘no immunity’ hypothesis. First, no test is absolutely fool-proof and false positives and false negatives, though infrequent, can occur with the RT-PCR test too. Second, it is possible, though unlikely, that for a small section of the population, the antibody response may be transient. Nearly all human infections produce a natural antibody response, which protects from reinfection. Some of these responses wane with time and require another challenge to establish a level high enough to be protective. In general, the antibody response to infection is more robust than the response to a vaccine. Vaccines are preferred because the much milder infections that they induce have a far lower mortality and morbidity than natural infection. There are very few infections, like the bacterial Haemophilus influenzae B, where the vaccine is engineered to produce a protective antibody response that the natural infection does not. The best evidence that SARS-CoV-2 is able to induce protective antibody production in humans comes from the observation that most people get rid of the virus without the help of any medicines.
The most effective response
We are faced with two alternatives, both of which will lead to loss of lives. An effective complete lockdown requires physical distancing at a level not possible in India without tremendous resources from the government. It has to be continued till a vaccine is available. If the lockdown is continued in the way it is now being done, it will decimate the poor. Using force to isolate the poor is not acceptable in a democracy. Mitigation measures, taking the people into confidence, and facing the pandemic by deploying available resources in the best possible way is the most ethical and effective response.
Dr. Jayaprakash Muliyil is an epidemiologist and former principal of Christian Medical College, Vellore and Dr. George Thomas is an Orthopaedic Surgeon at St. Isabel’s Hospital, Chennai. Views are personal
