Dr Nazrul Islam, a physician-epidemiologist and medical statistician with the Big Data Institute at the University of Oxford, co-authored the study Physical distancing interventions and incidence of coronavirus disease 2019: natural experiment in 149 countries in the British Medical Journal, with eight other experts.
He explained to Sputnik that whilst the report has its limitations (such as not factoring in the role of contact tracing or masks) it still offers a “novel” way of viewing the benefits of implementing social distancing measures early on, amid the COVID-19 pandemic.
Sputnik: How much better off are countries which implemented a lockdown closer to January 2020?
Dr Nazrul Islam: While it is intuitive that physical distancing interventions would reduce the COVID-19 cases, we wanted to estimate how much that effect would be. In other words, is it a 0.0001 per cent reduction, or a staggering 10 percent reduction? Our study found that the overall reduction in COVID-19 cases across the 149 countries examined was 13 percent, on average. However, this reduction was 14 percent, on average, in countries that implemented lockdown earlier as opposed to a 10 percent reduction, on average, in those that implemented the lockdown later.
Sputnik: So, if two countries which have relatively the same population size, one implemented physical distancing early on and the other one, waited, say 40 days, there's a 13 per cent difference in new cases?
Dr Nazrul Islam: What we did in our study is we compared one country with itself. That's the first bit of information. We did not compare Brazil with, let's say, Ghana, we compared India with India, Brazil with Brazil.
How did we do that? There is a date of physical distancing intervention, right? And so, before that, there is a slope, as in trajectory [of new COVID-19 cases], let's say it is increasing at a certain rate, we call it ‘incidence rate before’. Similarly, there would be an ‘incidence rate after’, and then we compared these two rates. I think that's the novelty of this research is that we did not compare across countries, but within countries before and after the intervention [by governments].
Some countries would have maybe 10 percent reduction. Some countries would even have no reduction at all— zero percent. Some countries would have a 20 percent reduction. And then we combined all the evidence from all the 149 countries by a mathematical formula, weighted average we call it. So, on average overall in the world in 149 countries, the rate of reduction [of COVID-19 cases after the implementation of social distancing measures] was 13 percent.
Sputnik: So, to what extent are these differences influenced or distorted by factors such as how well a country engaged in contact tracing, testing, and even reporting cases of COVID?
Dr Nazrul Islam: I think that's a very important question. First of all, of course not everything could be handled in our analysis. For example, track and trace, and face coverings or face masks. However, we only considered up to 30 days of intervention within each country expecting that there shouldn't be a substantial change in terms of testing pattern and other things within the country.
Of course, it is an assumption, which is untestable because we don't have enough data to see, like, did it really change much. However, we believe our findings are robust since we pooled data from a staggering 149 countries, and the overall evidence is pointing towards a beneficial effect on the reduction of COVID-19 cases.
Sputnik: If you have a 13 percent reduction in cases which isn’t necessarily a 13 percent reduction in fatalities, is it worth it? If you think about the other negative aspects of the lockdown such as reduced exercise, treatment and surgeries that were postponed, potential increase in depression and the economic implications of the economic consequences. How does that stack up with a 13 percent reduction in cases, in your opinion?
Dr Nazrul Islam: I think that is also a brilliant question. Is 13 percent a big deal? Well, because COVID-19 is affecting in the range of millions [of people], 13 percent in the context of millions is a huge number. That too is within the first 30 days of the policy interventions. Consequently, if you have low number of cases, then the pool of people for transmitting the disease, as well as the mortality would be a lot less.
Sputnik: Your research recognises the fact that the effectiveness of physical distancing measures is not completely conclusive. To what extent would that undermine the ability to come to a conclusion earlier social distancing measures are linked to lower COVID-19 figures?
Dr Nazrul Islam: Well, our results are robust, and they align with other similar studies and evidence. However, we phrased our finding to make sure we do not overstate our results. Research is an ongoing process, and I personally think it is arrogant to claim something conclusive based on one study. Being humble should not be interpreted as a weakness of the scientists or the research, rather it should be considered an appreciable humane quality.
Sputnik: Your paper noted that there was no evidence found of an additional effect of public transport closure when the other four physical distancing measures were in place. Does that mean if you do the other four physical distancing measures, it's not necessary to then close public transport?
Dr Nazrul Islam: Yes, I think that's one of the major findings of our study as well. The other four were school closure, workplace closure, and more importantly restrictions on public gatherings or mass gatherings and, and lockdown. This is quite intuitive as well. Practically, if the other four measures are in place, there would be fewer people using the public transport, and it would be much easier for them to maintain the physical distancing in the public transport. This is particularly important for people who work in service industry including hospitals and care homes.
Sputnik: So, it might not be necessary to have locked down in terms of people having to stay at home, if those other three measures were in place, school closures, restrictions on mass gathering or working from home?
Dr Nazrul Islam: We did find that, yes. If you have three of them in place, then the absolute lockdown may not be necessary. But the reason why we did not really emphasise much on that is because that came from 11 countries only, so it has to be taken with a bit of a caution.
Another important finding is that all the strategies that worked well had one component in common, and that is restrictions on mass gatherings.
Sputnik: Are there any other limitations, that you think people should be aware of, in addition to the ones that we spoke of?
Dr Nazrul Islam: I think the most important thing people think about is this data is not perfect. There are differences in ways countries are reporting the data. But this is not unexpected in the context of a pandemic. So, our objective was to get the best out of this imperfect data.
Also, our study did not analyse the effectiveness of other potentially effective measures such as track and trace, and facemasks. Also, facemasks should not be a replacement for physical distancing and vice versa.
Sputnik: Can you summarise any recommendations that you would make based on your research?
Dr Nazrul Islam: Physical distance measures are effective in reducing COVID-19 cases. In the context of millions of cases, an overall reduction of 13 percent is really a big number. And if you can reduce the number of cases, the overall pool of patients that can transmit the disease to other people will be reduced as well. This will, in turn, reduce the number of deaths. If you can implement other measures well, then we may be able to keep the public transport open particularly for those who work in the service industry.
