• Tuesday, Nov 24, 2020
  • Last Update : 09:23 am

OP-ED: Second wave lessons from around the world

  • Published at 02:10 am November 22nd, 2020
covid test

What have we learned about fighting Covid-19 so far?

As the northern hemisphere moves into winter, coronavirus rates are rising in parts of Europe and the US. Experts are warning of a long winter ahead as Covid-19 and influenza put the squeeze on hospitals and other health care facilities. In response to the threat presented by the second wave, European countries and many US states have instituted population lockdowns that involve varying restrictions on movement, meeting people, work, schooling, shopping, hospitality, and entertainment.

What have we learned and what other measures do we have in our collective toolkit?

Mass testing

China, having controlled the first wave of the epidemic and with fewer than 100 reported cases per day, now uses a mass testing strategy whenever a new cluster appears. This has been carried out efficiently using PCR (polymerase chain reaction) testing of batches of five to ten samples at a time, then going back to test individual samples if a batch tests positive. 

The rationale for this approach is to find people who did not know they were infected so they can be advised to isolate and therefore reduce transmission.

People are willing to wear masks and accept other interventions as part of a commitment to the greater good at the expense of individual freedoms. This is accompanied by strict enforcement from the government which has at times deployed drones using loudspeakers to rebuke citizens who are not following the rules.

In Europe, Slovakia instituted mass testing of their entire population of 4 million over two weekends during October and November. About 95% of the targeted population has now been reached and tested, with 38,000 positive cases being asked to go home and self-isolate. Slovakia also used rapid antigen testing, which despite having a variable false positive rate, can give results within 30 minutes, is cheaper than PCR, and can be done without the need for a specialized laboratory.

WHO has supported the development and facilitated access to affordable rapid tests, at less than $5 per test, particularly for low and middle-income countries.

Rapid tests have been trialled in other part of Europe, for example in Liverpool in the UK. In cases where there is a dedicated test site and trained personnel, these tests returned positive results for 99.6% of true infections, and returned negative results for 76.8% of people who did not have Covid-19.

The implications of this are that if there is a general positivity rate of 2.2% in the local population, as suggested by the most recent surveys, for every 1,000 people tested, 17 will be identified correctly as infected and advised to self-isolate, five uninfected people will be incorrectly identified as infected and unnecessarily advised to self-isolate, and three who are infected will be incorrectly identified as uninfected. Since those three people will probably have low viral loads, they may not be very infectious.

The upshot is that if people take up testing and follow the advice, this approach has the potential to reduce transmission and hence new infections by at least 50% in the short term.

Effective contract tracing

Vietnam has used aggressive contact tracing since the start of its epidemic, and there are currently less than 100 reported cases per day in the country, and no recent deaths. Anyone who is infected is hospitalized, which helps to enforce isolation, while contacts are isolated at home with the immediate neighbourhood placed under a local lockdown. There has been clear communication and the issue is seen as non-political and a matter of public health.

South Korea, meanwhile, has used retrospective contact tracing to investigate outbreaks and understand where transmission is occurring. As a result, many bars, night clubs, karaoke bars, and places of worship have been closed.

Taiwan, where there have been no reported deaths since May, has probably the most effective testing and tracing program. Cases are followed up twice daily by telephone, text messages, or home visits to reinforce the self-isolation message, and to offer support, which can include meal and grocery delivery. 

Crucially, contact tracing only works if it’s done properly. WHO stresses the importance of not just identifying cases, but following them up and giving support. They estimate that on average each case needs three days of work from the testing and tracing team. Clearly, this can only be feasible if the number of daily cases is brought down to manageable numbers, which is not the case in many European countries, nor in parts of the US.

Unfortunately, with case numbers as high as they are in these places, the best approach for Western countries getting through the winter seems to be to continue to use national or local lockdowns.

Jimmy Whitworth is Professor of International Public Health, London School of Hygiene & Tropical Medicine. This article previously appeared on The Conversation UK and has been reprinted by special arrangement.

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