Social distancing: is it time to stop?

Publicação: 9 de May de 2020

Study projects prolonged or intermittent social distance until 2022

Measures can be applied intermittently, according to the Covid-19 contagion rate. According to the projection, health authorities should monitor the transmission of the virus until 2024

Combating the new coronavirus may require a longer period of isolation from people. This is revealed by the study “Projecting the transmission dynamics of SARS-CoV-2 through the post pandemic period published in Science. North-American researchers estimate that, in order to maintain control of the new coronavirus, it may be necessary for the population to maintain measures of social distancing, albeit intermittently, until 2022, if there is no form of prevention, such as a vaccine, available in the coming months. According to Harvard scientists, there are two possibilities for reducing the duration of the pandemic and measures of social distance: increasing the capacity of the health system and introducing treatment that halves the proportion of infected people requiring hospitalization. The dynamics of pandemic and post-pandemic transmission of SARS-CoV-2 will depend on factors such as the degree of seasonal variation in transmission, the duration of immunity and the degree of cross-immunity between SARS-CoV-2 and other coronaviruses, as well as the intensity and timing of control measures.

To reach these conclusions, researchers at Harvard University School of Public Health evaluated a series of scenarios of how the virus could spread over the next five years. These estimates considered some variables. For example: whether or not the person recovered from the disease develops short or long term immunity, a doubt that still persists among specialists.

One of the authors of the research, Dr. Marc Lipsitch, recognizes that prolonged detachment is likely to have profoundly negative economic, social and educational consequences. “However, the damage to the health system that is foreseen if the distancing has not been taken for long enough, will be catastrophic”, he points out. Also according to him, longitudinal serological studies are urgently needed to determine the extent and duration of immunity to SARS-CoV-2. “Even in the case of apparent elimination, SARS-CoV-2 surveillance must be maintained, as a resurgence of contagion may be possible until 2024”, he adds. The researcher also points out that seasonality, immunity and cross-immunity estimates were used for beta-coronavirus OC43 and HKU1, based on time series data from the United States, to form a transmission model for SARS-CoV-2. “We project that recurrent outbreaks are likely to happen in winter, and that they are likely to occur after the most severe initial pandemic wave”, warns Dr. Lipsitch.

Another author of the research, Dr. Yonatan H. Grad explains that for the study, data on the spread of other types of coronaviruses that have been circulating in the United States for years and cause only common colds were analyzed. “We studied the immunity and seasonality characteristics of these viruses, that is, when there is more contagion during the year and we found that it can circulate at any time. However, due to the scenarios observed by our group, contagion may have more or less acute peaks depending on the season and local characteristics”, he points out. Still according to him, the little more than three months since the beginning of the disease are still insufficient to conclude whether the infection by the new coronavirus confers permanent immunity to Covid-19 or not. “If immunity is permanent, the virus can disappear after five or more years after causing a major epidemic. If it is not, it is likely that the new coronavirus will enter regular circulation with outbreaks from time to time, as it does with some agents of the flu”, he points out while observing that there is still the possibility of infection by other types of coronavirus to confer some degree of crossed immunity against Covid-19.

Professor Lipsitch recalls that the objective of the modeling is to identify probable trajectories of the epidemic under alternative approaches, to identify complementary interventions, how to expand the capacity of the Intensive Care Units (ICU) and to identify treatments to reduce the demand in of ICUs, as well as to stimulate innovative ideas to expand the list of options for putting the pandemic under control in the long term. “Our model presents a variety of scenarios designed to anticipate possible dynamics of transmission of SARS-CoV-2 under specific premises. We do not take a position on the desirability of these scenarios, given the economic burden that sustained distance can impose, but we do observe the potentially catastrophic burden on the health system if the distancing is ineffective and/or is not sustained long enough”, he concludes.

On social distancing, Dr. Babak Javid, a professor at the School of Medicine at Tsinghua University in Beijing, and consultant in infectious diseases Cambridge University Hospital, says that we need to think carefully about facilitating the lockdown. He emphasizes that there are huge economic consequences and that economic disparities lead to health disparities. “However, this does not mean that we need to abandon all social distancing. I believe that over the next year we will see a phased approach and that will depend a lot on the context. Crowded urban areas will have a much greater risk than rural areas”, he comments.

Fighting covid-19: are the costs worth the benefits?

For Dr. John Appleby, Director of Research and Chief Economist at Nuffield Trust, London, UK, professor at the City Health Economics Center, City University and the Institute of Global Health Innovation at Imperial College, the short answer is yes. However, according to him, this calculation will become progressively more difficult as the lockdown and other measures last. “For now, the impact of ‘doing nothing’ against covid-19 has been immense in terms of loss of life. However, as we can see, many countries are gradually exploring ways to slowly relax lockdown measures as they begin to see themselves on the way to reducing new cases and deaths by covid-19. This will be a gradual and cautious process”, he says.

European authorities recently released a guideline to phase out coronavirus containment measures and also warned that getting out of the lockdown will take long and will require much cooperation. The President of the Commission, Ursula von der Leyen warned that countries’ failure to work together on their exit strategies could lead to a dangerous second wave of covid-19. “The road back to normality will be very long”, says the script, warning that masks, gloves, tests and applications to track people’s movements will become routine and that a full economic recovery will likely have to wait until the vaccine is approved.

Professor Appleby agrees that abandoning the lockdown is going to be a longer process than people can imagine. “It will not be as simple as ‘turning off a switch’, among other reasons, because I suspect that people will impose their own lockdowns until they feel really safe, which can happen only after an effective vaccine”, he says. Asked if it is time to end social distancing, the professor recalls that clinical and epidemiological opinions report that social distance is still totally necessary. For him, even where governments started to relax the lockdown and social distancing measures (i.e. Wuhan and Berlin) it seems that many people still have individual decisions not to go to work or to visit crowded environments due to health concerns.

Finally, Dr. Appleby reflects on the importance of social care and future subsidies to health and social care. “Shelters for the elderly were particularly affected by the covid-19 and I think this increased the population’s concern about how much they invest in social care. I believe that people are also questioning how much they invest in the National Health System (NHS), the UK’s public health system, and that there will be a greater public interest in expanding investments in public health in the future”, he concludes.

Masks are becoming mandatory almost everywhere in the world

Most of us should probably ask about the protectiveness of a mask, especially of those made of fabric; can it protect us from Covid-19? Professor Appleby clarifies that the evidence on its effectiveness is somewhat controversial. “But they are cheap, so perhaps it is a case of ‘better safe than sorry’, he justifies. However, the sense of ‘personal protection’ loses the main reason when requests for increased use have gained momentum worldwide.

Professor Babak Javid is adamant that people should wear masks. “We know that Covid is transmitted by droplets from the mouth and nose. We also know that about half of the transmissions occur before anyone knows they have been infected. We know that face masks can block most (60-90%) of infectious droplets and viruses. So, it makes sense that everyone should wear masks”, he argues. The scientist explains that the main benefits of wearing a mask are for other people, that is, ‘your mask protects me and my mask protects you’. “So, to make an impact, most people (more than 50%) should use them. In this way, the general transmission of viruses can be reduced”, he admits. Still according to Dr. Javid, the main benefit will be in environments, for example, indoors and on public transport, where physical distancing is not possible.

However, the great risk of recommending use by the general population, even for those who do not show symptoms of infection, is in the false sense of safety. According to the professor, this is a common objection, but there is no evidence to support it. “In Hong Kong, the population (> 97%) has been wearing masks for three months and none of this has happened. In the Czech Republic, masks have been mandatory for more than six weeks and, again, no evidence of risk. If these risks were real, we would see reports of increased transmission events in these countries, but, in fact, we find the opposite: a consistent reduction in transmission”, says Dr. Javid while adding that the masks would be supportive to other measures. “We don’t see people taking risks because they washed their hands, do we?”, he compares. And if wearing a mask causes people to start going out more, to interact, to reduce their distance from other people, can this cancel out the possible benefits of wearing and increase the risk of transmission? For Dr. Javid this argument is not valid. “I’m not saying that we should abandon other measures, but the reality is that, at times, intimate interactions are inevitable and cannot be avoided. Obviously, this would be safer if both parties wore masks”, he details.

Masks as a barrier

According to Professor Javid, there is very robust scientific evidence that the masks block the transmission of contagious droplets by at least 70%, regardless of whether they are cloth or medical mask. However, according to him, what is lacking is evidence of a ‘randomized controlled study’ for the use of masks by the population against Covid-19. “But this kind of evidence is lacking for hand washing, physical distance and lockdowns as well”, he says. The professor reports that there are some trials of wearing a mask to prevent the flu, and they have not shown benefits for masks in general, but they have also shown no benefits for washing hands. Still according to him, it is important to note that in these studies most people did not wear masks because they were not afraid of getting the flu. The professor stresses that Covid is a very different situation. Finally, Dr. Javid reiterates that to make a big impact, masks should be used by the majority of the population, at least 50%, and, ideally, more than 70%. “Wearing a mask for Covid is an act of altruism, we need to think that we are protecting others and how we can help in that regard”, he says.

See more:

Germany aggravates epidemic after easing isolation rules

Why do some break social isolation? Science explains

Isolation can come and go for 2 years, says a Brazilian at the WHO

Covid-19: WHO warns of risks of suspending containment measures

Coronavirus: what is the ‘intermittent social distance’, which can last until 2022

Use of a mask does not dismiss from social isolation and hygiene