DISEASE-related estimations give information on the number of the diseased, number of severe cases, outcome of the disease such as whether cured, suffered from permanent damage to the body or death from the disease, etc. The estimations usually are based on a numerator and a denominator. The denominator should include (i) all those infected but might not show any clinical feature — one estimate from China puts this figure in 20–80 per cent, on an average about 30 per cent; (ii) all those who show mild clinical features, up to 80 per cent, as we know, and (iii) all those who show severe and critical manifestations, which may be 20 per cent, and 5 per cent of this 20 per cent respectively.
For estimating the case fatality rate of COVID-19, the numerator would be the number of people who died of COVID-19 and denominator all those who were infected. The possibility of including all the infected people, silent or overt, in the denominator will be lower, as fewer of those who were to be in the denominator will, in fact, be identified, counted and included in the denominator while the possibility of including all those who died of COVID-19, the numerator, will be higher, because missing of death, that is easily identifiable, will be fewer. In this situation, the estimated case fatality rate will be high wrongly (this is what is happening now). The case fatality rate may also fluctuate based on its definition, for example in Italy, when testing was started only for severe cases, the case fatality rate jumped from 3.1 per cent to 7.2 per cent. The magnitude of a disease is measured by the incidence rate, in an acute and short-lived disease like COVID-19. It will remain unknown, when the denominator, ie all those who were supposed to be tested for finding disease in them, was not selected or not selected randomly.
COVID-19-related estimates
THE case fatality rate was noted to be age-specific. In Spain, Italy, South Korea, and China by March 21, there was no case fatality in children less than 10 years of age. Among the children aged 10–19 years in Spain, the fatality rate was 0.4 per cent (4 in 1,000 children). Italy and South Korea have reported no fatalities for this group (10–19 years); China reported a case fatality rate of 0.2 per cent in this age group. In the United States, there had been no death among people less than 20 years of age. Among the people aged 20–29 years, fatality from COVID-19 was 0.3 per cent in Spain. Italy and South Korea have reported no fatalities for this age group; China reported 0.2 per cent fatality. In the United States, among 20–44 years old, fatality was 0.1 per cent. Among the adults of 30 years to 49 years of age, the fatality rate were 0.2 per cent, 0.3 per cent, and 0.2 per cent in Spain, Italy and China respectively. The case fatality was 1.4 per cent in Spain among people aged 50–69 years. In this age group, fatality ranged from 0.4 per cent to 3.6 per cent in Italy, China and South Korea. In the United States, fatality was 0.5 per cent in patients aged 45–54 years, 1.4 per cent in patients aged 55–64 years and 2.7 per cent in patients aged 65–74 years. Among the patients aged more than 70 years, the case fatality was 11.4 per cent in Spain; in Italy, China and South Korea, it ranged between 6.2 per cent and 20.2 per cent. In the United States, the case fatality rate was 4.3 per cent among people aged 75–84 years. Among people above 85 years of age, fatality was 10.4 per cent in the United States. In Iceland, which has the highest rate of population-based infection (26,762 per million population), the case fatality rate was 0.21 per cent.
The epidemic curve in China peaked in January 23–26 and then began to decline up to February 11. Most cases belonged to 30–79 years of age (87 per cent), 1 per cent aged ≤ 9 years, 1 per cent aged 10–19 years, and 3 per cent 80 years or older. Also, the case fatality rate in China was higher in early stages of the outbreak (17 per cent for cases from January 1 to 10), which reduced to 0.7 per cent after February 1.
Patients with no co-morbidity, in China, had a case fatality rate of 0.9 per cent, while critical cases (respiratory failure, septic shock, and/or multiple organ dysfunction/failure) had a rate of 49 per cent. In Italy, there are two reasons of a high COVID-19 mortality — higher rate of smoking than in many European countries and 88 per cent due to co-morbidity (76 per cent had hypertension, 36 per cent diabetes and 33 per cent ischemic heart disease, the heart not getting enough blood/ oxygen). On the Diamond Princess, the cruise ship, initial estimates reported six deaths out of 705 who tested positive, a case fatality rate of 0.85 per cent. All six deaths occurred in patients >70 years of age.
Table I shows deaths among COVID-19 patients with some critical co-morbidities and death among patients with the critical morbidities without COVID-19. Table I shows that most of those who died of COVID-19 in comorbid conditions had a likelihood of dying from the critical morbidities anyway (71 per cent to 80 per cent probability). Table II shows the risk of death from COVID-19 by age, with comorbidity (underlying cause).
Deaths from competing causes
THE number of COVID-19 fatalities is small, would remain to be small probably, compared with the 12 million total number of people who have already died this year from all causes globally. Without COVID-19, 60 million people will die expectedly in 2020, with 18 million people dying of heart diseases, 10 million of cancer, 6.5 million of respiratory diseases, 1.6 million of diarrhoea, 1.5 million in road incidents and one million of HIV/AIDS. Suicides could number 800,000.
In China, COVID-19 mortality occupies the 49th position among all the killer diseases; in Italy, it is the eighth important cause of mortality because of its high number of elderly population. Notice may also be taken of the fact that because of attention on COVID-19, some emergency patients might have died unduly. Lockdown, isolation and quarantine also robbed people of developing natural (herd) immunity, which could give longer-term protection to people. The next advent of SARS-CoV-2, therefore, may be equally devastating, s it will get a sizeable population to infect.
Proposed alternate strategy
WHAT the above discussion brings us to? Is the strategy of asking everyone to hide behind the four walls of their homes both epidemiologically correct and economically efficient? How many more people would die of COVID-19 if they were exposed to SARS-CoV-2? Contrarily, how many more people might die next time when exposed to a more fatal form of the virus if they are not exposed to the virus now? Right now against a crude death rate of 5 per 1,000 people in Bangladesh without COVID-19 (which is 900,000 deaths a year or 2,466 a day), 27.1 per cent of it occurs among infants. Death falls after that age up to 45 years, to about 2 per cent. At 45 years of age proportionate mortality is 4.5 per cent, increasing to 14.1 per cent among people above 60 years of age, going to 27.5 per cent among people aged 70–74 years and 81.9 per cent in people above 75 years of age. The same trend of death is seen among people of these different ages from COVID-19.
What is happening to the economy? How many people would die from poverty and under-nutrition consequently in the long run due to the lockdown? Let economists churn the figure out. But we are staring in the face of a discomforting economic slump.
Based on the analyses, we, therefore, suggest an alternate strategy. We propose to lift the lockout and let people, with minimum risk of dying (20–49 years), get exposed to the virus and develop herd immunity. We cannot prevent the various competing deaths in people even if we save them from COVID-19. Those competing deaths are in fact much higher in number. If we are not preventing those deaths, why are we exhausting all our resources to save people from only one disease? As part of the proposed strategy, we suggest keeping those who are vulnerable, ie those with critical co-morbidity, those who are aged, children less than one year of age and people with other immune-compromised conditions, etc. under dedicated attention to protect them from exposure. For example, families with elderly/debilitated members, members with co-morbidity and infants with their family caregivers should be isolated from those members of the family who have to go out for occupational and educational reasons. We encourage this strategy also in light of the finding that SARS-CoV-2 gets less fatal gradually.
Since managing too many severe cases of COVID-19, all happening within a short period of time, will be beyond the capacity of the health systems, we propose to lift the lockdown following a gradient of the economic vibrancy. But the health systems should be strengthened in these GDP producing areas so that, when necessary, those who need critical care can get it. What would be the size of this need may be worked out. It is also suggested that authorities and management arrange lung capacity enhancing exercises for their staff several times per day to cope efficiently when any comes down with COVID-19 and also encourage them to adopt other measures touted by some cured people, eg drinking and gurgling with hot water, taking lots of citrus fruit, etc. Alternatively, antibody tests may be instituted for the staff. Those who are found to exhibit the presence of antibody in their blood may be allowed to resume their offices. Antibody tests may be sponsored by the employers for their staff. It should be conducted by a dependable laboratory. Antibody may not impart complete immunity but will reduce the impact of a re-infection. This is a managed or controlled exposure strategy towards herd immunity.
AM Zakir Hussain is Working Group member of Bangladesh Health Watch (BHW), former director, Primary Health Care and Disease Control; former director, IEDCR, DGHS; former regional adviser of SEARO, WHO and former staff consultant, Asian Development Bank, Bangladesh.
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