worrying situation of the COVID-19 epidemic in Europe, particularly in Spain, calls for immediate actions to save lives in the short term, with the longer-term goal of reaching the threshold of immunity to the virus while incurring the lowest human and socioeconomic costs possible.
Building on evidence from previous pandemics and data from mathematical models that combine real parameters and some assumptions, we can set forth a series of clear actions and recommendations that should be considered.
The theoretical framework
In the absence of a global attenuation, it is likely that the epidemic will only cease once
a certain proportion of the population has acquired immunity against the virus. In the case of SARS-CoV-2, estimates indicate that at least 60% of the population needs to acquire immunity to the virus , either as a result of having recovered from the infection (assuming that immunity is long-lasting and that the virus will not mutate significantly), or as a result of a vaccine (which will not be available for at least one year, in the best of cases).
In the absence of a global attenuation, it is likely that the epidemic will only cease once a certain proportion of the population has acquired immunity against the virus
Until we reach the immunity threshold, we can assume that
many deaths will result from a saturation of the health systems. In fact, around 30% of infected people may be asymptomatic (according to data from the Diamond Cruise ship and a study with 565 Japanese evacuees), and among those who do develop symptoms, the symptoms will be mild or moderate in 84% of cases. Consequently, the mortality associated with this pandemic will occur mostly among the elderly and those with chronic diseases or immunosuppression (direct deaths), as well as people who cannot receive care due to collapsed health systems (indirect deaths).
What to do? The
models for COVID-19 indicate that in the absence of a vaccine or effective treatments, viral transmission can be delayed but not avoided. They also indicate that mitigation (measures to isolate cases, quarantine contacts, social distancing for people aged 70 and older, school closures, etc., to different degrees according to the situation) will not be enough to avoid exceeding the limit of intensive care beds available in Spain today. In turn, suppressing transmission (through rigorous lockdown measures for five months) would lead to a second peak of the disease in the winter of 2021, once the measures are lifted and if more dynamic control measures are not implemented.
1918 flu pandemic clearly demonstrates that suppressing transmission cannot be achieved without reaching the threshold of immunity: the epidemic had three peaks during one year. This could be have been due to a variety of factors such as the closure and opening of schools, fluctuations in temperature and humidity, public health responses, and individual behaviour.
VIDEO Act now with a long-term vision In the short-term
For Spain, the immediate priority is to reduce the pressure on the health system and save lives. This requires:
Allocating all possible resources, both public and private, to rapidly increase health system capacity. This means providing health centres with the necessary supplies, particularly ventilators and personal protective equipment for healthcare workers; reinforcing diagnostic capacity with PCR and rapid diagnostic kits at points of care; building makeshift hospitals; using other facilities such as hotels for less severe cases and for medical staff, thereby avoiding household transmission; and recruiting and training more healthcare workers. Reinforcing the monitoring of cases isolated in their homes, and the compliance with hygiene and preventive measures by other household members. Increasing the capacity to identify and trace case contacts , with the support of digital tools and data analysis. Increasing the lockdown level , authorising only basic services for the time needed to bend the epidemic curve. For this to be achieved in the shortest time possible, the measures described in the above points must also be implemented. This total lockdown can evolve into a partial one (work is allowed) and eventually into intermittent lockdowns, according to the evolution of the epidemic and of health system capacities. In the medium and long-term
In the longer term, the priority is to achieve the threshold of immunity at the lowest possible human cost. For this to happen, a second phase with the following actions should be implemented once the current exponential growth has been controlled:
Perform massive diagnostic tests (PCR) to detect cases of active infection and isolate them, as well as rapidly identifying and quarantining possible contacts. Perform mass serological diagnostics in order to provide individuals with a serological ID that allows them to work and travel, to protect healthcare workers, and to understand the dynamics of transmission within the community. Invest the necessary resources to test drugs (chloroquine, azithromycin, antiviral drugs) that attenuate – but do not prevent – the infection (and thereby act as an imperfect vaccine), with the aim of generating immunity among high-risk contacts. Consider long-term social distancing for the most vulnerable populations until a vaccine or effective treatment becomes available. Conclusions
Without an available vaccine, infections can be delayed but cannot be avoided. Therefore,
it is urgent to increase the capacity of the health system and reinforce compliance with those measures aimed at reducing transmission .
It is urgent to increase the capacity of the health system and reinforce compliance with those measures aimed at reducing transmission
Given the exponential increase in cases and deaths,
more restrictive measures are needed and a total lockdown should be implemented. However, total lockdowns cannot be maintained for long periods of time without causing indirect deaths due to their high socioeconomic cost. Therefore, the lockdown should be limited in time and accompanied by the measures described above . The lockdown period should be used to develop a sustainable mid-term strategy that includes diagnosis and isolation of cases, identification and quarantine of contacts, and continued efforts to develop preventive treatments.
Finally, it may be necessary to consider implementing
intermittent lockdowns to reduce a second (or third) wave of infection .
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