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Dr Deepti Gurdasani in Conversation | Covid In Wales

Dr Deepti Gurdasani, a senior lecturer in clinical epidemiology at Queen Mary University in London, has in recent months become a vocal critic of the UK Government’s response to the COVID-19 pandemic. As the Welsh Government moves toward the Green phase of its plan to ease out of lockdown, she talked with Kevin McGrath about her concerns that Wales is set to return to pre-lockdown levels of COVID transmission.

You’ve recently completed a study modelling the impact of the UK Government’s measures to ease lockdown in England. What conclusions did you reach about how those measures would impact the level of COVID-19 transmission, and could those outcomes be applied equally to Wales?

Dr Deepti Gurdasani: Many public health experts have noted that the easing of lockdown has been relatively early and rapid in England, despite going into lockdown relatively late. By early, I’m referring to the point in the pandemic, rather than absolute time as levels of cases and deaths in England were very high when we started easing lockdown. We’ve pointed out in our study that easing lockdown at a point where community transmission is relatively high will result in thousands of excess cases and deaths – relative to holding off on easing lockdown until we achieve a near-elimination scenario.

Data from other countries also supports this notion: that suppression, even to relatively low levels, doesn’t really work as a long-term strategy, as community transmission will inevitably increase once we ease the measures that are holding the virus in check.

While Wales has been more cautious with the lifting of lockdown measures, the fact is that without a strategy to really mitigate the impact of easing lockdown, we will likely see a surge in community transmission. We can already see this from the Welsh data, where we have seen a consistent rise in daily infections and daily deaths over the past couple of weeks. We’ve also seen several clusters of transmission emerge in specific settings such as hospitals and local meat processing plants.

What will life in Wales look like over the next six months if we follow the same path as England rather than adopting a zero-COVID strategy similar to that seen in Scotland and Northern Ireland?

Dr Deepti Gurdasani: The Welsh Government’s strategy isn’t clear, but it does appear to be a strategy of suppression rather than elimination, which suggests that a certain level of community infection is seen as ‘tolerable’. Countries that have followed this path have generally all seen increases in infection after easing lockdown and opening borders – and one would expect the same to happen in Wales, unless they commit to a zero-COVID strategy.

There is absolutely no reason to think that easing lockdown will not bring us into the same position as March, as the primary measures holding the virus in check are social distancing and breaking transmission networks through school and workplace closures. It’s clear that we don’t have a working test, trace and isolate strategy, even in Wales, where there have been significant delays in passing on test results to those infected, potentially resulting in delays in identifying contacts and isolating them. Similarly, there isn’t widespread mandatory mask use which may have mitigated the impact of easing lockdown. Studies have also made clear that it is unlikely that there is widespread immunity across populations, and only a small proportion of the population has been infected so far.

Given all this, the only way to control the pandemic is to aggressively try to eliminate the virus, rather than taking a reactive whack-a-mole approach where we need repeated and continuing restrictions to control spread to a given level. Almost all countries that have adopted such an approach have seen surges in infection when restrictions are eased – even with testing and tracing systems that are vastly superior to ours.

How would a zero-COVID strategy work in practice?

Dr Deepti Gurdasani: The idea of a zero-COVID strategy is that we aim to completely eliminate the virus within the community and then prevent the virus being imported from outside using strict quarantine measures. In this setting, life can return to near-normal, as there is no virus spreading in the community. This is different from the current strategy in some European countries and in England and Wales, which is ‘suppression’. Suppression only aims to keep levels of transmission below a certain mark, bringing in restrictions whenever those transmission rise above that mark.

Global experience shows that suppression is difficult to maintain, and as restrictions are eased we’re likely to see surges of virus. Suppression is therefore maintained by monitoring, and imposition of restrictions as and when surges in transmission are seen. This means that we have to continue to maintain measures that control the virus, including social distancing, mask use etc.

An aggressive, multi-pronged public health strategy is needed to eliminate the virus. This strategy may include widespread mask use (in all spaces), aggressive rapid testing of cases, contact tracing and isolation to prevent asymptomatic and pre-symptomatic spread. It would also require strict maintenance of quarantine for all travellers entering the country. It may require additional measures such as a defined period of stay at home measures and school and business closures for a period of time to break transmission networks. The approach has to be multifaceted, and planned rather than reactive. And be supported by clear and simple public health messaging. The duration of such measures will depend on the baseline level of infection when restrictions are imposed, and the compliance with and the synergistic use of multiple approaches to eliminate infection.

One feature of the Welsh Government’s public health messaging relates to the Chief Medical Officer’s stance on face masks. Throughout the pandemic Dr. Atherton has downplayed the importance of masks, recently claiming that mandating their use ‘would not be proportionate’ given the present levels of transmission. Are lives being put at risk in Wales as a result of his dissenting view on masks?

Dr Deepti Gurdasani: England and Wales have acted late relative to many other countries across the globe with regard to public use of face masks. In Wales, mask wearing is not mandatory in shops. We know that COVID-19 is spread while infected people are asymptomatic, which means that control measures based on symptoms are inadequate. Several studies show efficacy of reduction in infection spread with mask use in different settings, with the level of protection at population level likely to depend on widespread use. While the absolute extent of reduction at population level and the mode of transmission of COVID-19 is not clearly understood, governments have a duty to follow the precautionary principle and encourage widespread mask use. Most public health bodies now recommend this across the globe, and most South East Asian countries that showed early success in COVID-19 control adopted widespread mask use months ago. Critiques of adopting mask use as a public health policy suggest that mask use may result in ‘risk compensation’ behaviours, whereby those wearing masks may feel a false sense of reassurance and take risks that they wouldn’t were they not wearing a mask.

Current evidence does not bear this out in almost any context (e.g. helmet use on bicycles); indeed, there is evidence to suggest that people who engage in one protective behaviour may become more likely, rather than less likely, to engage in related behaviours. The fact is that we cannot wait for large randomised studies of mask use in the middle of a pandemic. Outbreak control is dependent on making the best decisions in the midst of uncertainty. And while there may be uncertainty around the exact efficacy of mask use at population level against a background of different levels of community transmission, there is reasonable evidence to suggest that this measure would reduce transmission if used widely.

As others have said, we would not expect large randomised studies of seatbelt use to prove that people should use seatbelts. Nor do we look at the cost of putting seatbelts into cars to weigh the benefit against preventing deaths due to road traffic accidents, even though road traffic accidents are rare. A similar strategy should be adopted for mask use, given the huge impact of COVID-19 on communities. This is a simple strategy, that if effectively communicated and implemented could have a considerable impact on COVID-19 transmission; it would be negligent not to adopt this, especially given the rising infection rates in England and Wales. In the context of the continuing easing of lockdown restrictions within Wales and rising community spread, mask use is a measure that would be key to curbing spread, alongside aggressive test, trace and isolate measures.

With the new school year fast approaching, what is your understanding of the debate around school safety in Wales?

Dr Deepti Gurdasani: There is rapidly accruing evidence that children get infected, potentially at the same rate as adults. Indeed, a large study from South Korea recently showed that 10–19 year old children may transmit the virus at a higher rate than adults in households. There is no reason to think that children would not be able to transmit in the school setting if they can transmit within households. The ONS survey carried out in the UK suggests that children are as susceptible to COVID-19 as are adults. Serological studies also bear this out. Evidence from a JAMA Pediatrics article is consistent with the idea that infected children harbour virus and carry virus in oral and nasal passages, with younger children actually carrying several fold higher levels of virus than adults. How this translates to transmission is unclear, as the presence of high virus levels doesn’t necessarily correlate with increased transmission.

More recent evidence from emerging clusters of infection in Israel and Georgia suggests that children above 6 years get infected at the same, or higher rates than adults, and do contribute to spread of infection. On the face of it, these recent studies supporting an important role for children in transmission appear to contrast with some earlier evidence from different regions, where often in households during lockdown, children were thought to be less likely to be contributing to spread than adults. Many limitations of these studies are now recognised.

We now know that while children are potentially as likely to get infected as adults, they are less likely to manifest symptoms, or manifest very mild symptoms. This means that they are less likely to be identified as the ‘index case’ (the first person who was infected in a cluster), and primary infection is more likely to be attributed to symptomatic adults within the household. Given that most regions have implemented symptom-based testing, it’s likely that infections in children have been substantially underestimated in previous studies. To really understand the role children play in transmission, we need to implement regular testing in schools, including that of asymptomatic children, as has been done in some parts of Germany. A second limitation of many of these studies is that they were carried out during a period in which schools were closed, which limited our ability to observe child-child transmission.

It is also likely that the increased transmission within schools depends on context, such as baseline community levels of infection. European countries have reported few outbreaks in schools since reopening; however, it is important to consider that schools reopened during a period when community transmission was quite low in many European countries.

The only way to really reduce transmission in schools in the longer term is to reduce or eliminate community transmission. This is another reason to consider adoption of a zero-COVID strategy: to make schools safer for children, and adults and vulnerable people who live with children.

There have been more than a few media reports recently that real progress is being made in the search for a vaccine. Suddenly, the idea has taken hold that we may have a vaccine, at least for health workers and the most vulnerable members of society within six months. Is that a view that you share? 

Dr Deepti Gurdasani: I’m not as optimistic about a vaccine becoming rapidly available as potentially many others are. I’d be very happy to be proven wrong on this.

My view is that a vaccine will take longer. It’s unclear what the efficacy will be in prevention of infection and reducing severity of infection and how long any resulting immunity will actually last. We haven’t been able to create a vaccine for any other coronavirus as yet, and while there are early promising results, we’re still quite far from a safe and effective vaccine that can be administered at population level.


Dr. Deepti Gurdasani is a clinical epidemiologist and statistical geneticist at Queen Mary University of London.