The use of masks, social distancing, and three other nonpharmaceutical interventions (NPIs) were efficient at containing transmission of the novel coronavirus during the COVID-19 pandemic, thus preventing widespread collapses of health systems in many countries prior to vaccines becoming available. These strategies proved especially useful when implemented together and in the earliest stages, suggests the scientific evidence presented in a series of reviews published in the journal Philosophical Transactions of the Royal Society A in August.
“There is sufficient evidence to conclude that early, stringent implementation of packages of complementary NPIs was unequivocally effective in limiting SARS-CoV-2 infections,” said Dr. Mark Walport, Foreign Secretary of The Royal Society, the British science academy that publishes Philosophical Transactions, and leader of the group of experts who carried out the review studies. “That does not mean every NPI was effective in every setting, or at all times, but learning the lessons from the wealth of research generated in this pandemic will be key to equipping ourselves for the next one,” he concluded.
In March 2020, well before vaccines were available, countries around the world began adopting sets of measures — in different formats, scopes, and intensities — that altered how society functioned and how people coexisted, representing the greatest interference in the daily lives of the global population since the Second World War. Based on experience from previous pandemics, such as the 1918 Spanish Flu, health authorities and experts advised governments to take action, including making the use of masks mandatory in certain situations and imposing social distancing and lockdowns, even before anyone knew exactly how SARS-CoV-2 would behave or whether such measures would be effective against it. Some of these interventions, especially social distancing and lockdowns, were quite unpopular due to their significant economic and social impacts, particularly on the most vulnerable populations. But they were considered necessary to combat a virus that spreads very quickly and against which there was no immunity.
Léo Ramos Chaves / Revista Pesquisa FAPESPStay-at-home orders reduced transmission of the new coronavirus by 50%, on averageLéo Ramos Chaves / Revista Pesquisa FAPESP
After the initial, critical phase of the pandemic, Walport assembled six groups of experts and asked each one to review the most important studies into the five main NPIs adopted to contain the virus: use of masks; social distancing and lockdowns; test, trace, and isolation; international border control; and environmental controls. The impact of communications on the acceptance of these measures was also analyzed.
Masks
A group led by epidemiologist Christopher Dye of the University of Oxford, UK, analyzed 75 studies that measured whether the use of masks reduced the transmission of SARS-CoV-2 in various countries. Thirty-five were carried out in communities and 40 at health centers. Almost all were observational studies, in which the researchers monitored the effects of using masks versus not using them, without interfering. Of the 45 studies that assessed whether face coverings reduced the number of people infected, 39 (87%) identified a positive effect — some recorded a decrease of just over 10% in the total number of individuals with the virus or symptoms of COVID-19. Of 18 studies that analyzed the impact of making masks mandatory, 16 concluded that the measure reduced the infection rate. “In general, the body of evidence analyzed demonstrates that face masks work,” says epidemiologist Expedito Luna of the School of Medicine at the University of São Paulo (FM-USP), who evaluated the report at the request of Pesquisa FAPESP.
Seven studies indicated that N95 masks provided more protection than surgical masks, although five other studies found no difference between the two. “At the beginning of the pandemic, when there were not enough masks available for everyone, the use of fabric masks was better than nothing, but the report makes it clear that those of better quality are more effective at reducing transmission,” says Pedro Hallal, an epidemiologist from the Federal University of Pelotas (UFPel), who also analyzed the studies reviewed in Philosophical Transactions.
Among all the interventions evaluated, social distancing proved the most effective. Orders to stay at home, maintain a minimum distance from other people, and restrict the number of people at social gatherings have repeatedly been linked to a major reduction in SARS-CoV-2 transmission.
Léo Ramos Chaves / Revista Pesquisa FAPESPTesting, tracing, and isolating infected people also showed potential to reduce the spread of the virusLéo Ramos Chaves / Revista Pesquisa FAPESP
Epidemiologist Christi Donelly of Imperial College London, UK, and her team reviewed 338 studies on nine social distancing measures. Almost half of the studies (151) evaluated the impact of stay-at-home orders, which in some cases included more restrictive actions, such as lockdowns. One hundred and nineteen of them found a significant reduction in the number of cases and deaths. The average drop in virus transmission was 50%, although the values varied considerably (from 6% to 81%) between the studies, which used different approaches and analyzed different populations with different forms of restrictions.
“Keeping people at home greatly reduces — and can practically eliminate — transmission of the virus for a period of time,” explains Hallal. “In Brazil, it did not work because they wanted to implement social distancing in a way that would not disrupt economic activities.” According to Eliseu Waldman, an epidemiologist from USP’s School of Public Health, social distancing clearly exposed the social differences in Brazil. “A large part of the population was unable to put the measure into practice because they needed to leave the house to get something to eat every day,” he states.
A team led by Elizabeth Fearon, an epidemiologist from University College London, UK, looked at 1,181 studies and found only 25 that empirically measured, at a populational level, the strategy of testing people suspected of being infected, tracing individuals with whom they had had contact, and isolating those confirmed as infected. However, due to the diverse range of approaches adopted, it was not possible to compare data for a single impact metric. “In general, these studies showed that testing and/or contact tracing were associated with reductions in transmission,” the researchers wrote.
Although most countries introduced travel restrictions during the pandemic, health policy expert Karen Grépin of the University of Hong Kong and colleagues found few studies examining the effectiveness of these interventions. According to the researchers, national case studies, such as one carried out in New Zealand, have shown that comprehensive border control policies can reduce but not eliminate the number of infected travelers. Travel restrictions from specific countries had a moderate effect on transmission, but quickly became less effective as the number of cases increased. Quarantining inbound travelers was considered more effective at reducing transmission of the virus.
A team led by Shaun Fitzgerald, an engineer from the University of Cambridge, UK, searched the scientific literature for evidence that environmental control measures — such as improving ventilation in closed spaces, filtering air, and disinfecting surfaces — could help reduce virus transmission. Of 14,000 articles identified, only 19 had been peer-reviewed. According to the authors of the review, the papers suggest that environmental controls are capable of reducing SARS-CoV-2 transmission when applied in enclosed spaces.
A group led by sociologist Simon Williams of Swansea University, Wales, reviewed the effectiveness of communication strategies at encouraging people to adhere to NPIs to control COVID-19. Thirteen articles were analyzed, all of which examined efforts in the United Kingdom exclusively. Trust — in the government, scientists, and health authorities — was the factor that most impacted the effectiveness of communications, having been mentioned in 10 of the 13 studies. Low trust in government led to lower adherence or to higher belief in conspiracy theories. The clarity and consistency of the message were just as important. “Mixed messages” led to confusion and in some cases a lack of compliance, the researchers said.
The report makes it clear that more focused studies are still needed to better understand the effect of each intervention. In the studies analyzed, many NPIs were adopted simultaneously, which made it difficult to separate the impacts of each. Luna, from USP, also points out that the social and economic consequences of the measures were not evaluated. Despite the limitations, Hallal says that the report organized by Walport is important because it adds empirical evidence to what was already known in theory or had been previously demonstrated by isolated studies. “These reviews showed that several interventions that we recommended a thousand times during the pandemic were effective. Many deaths could have been avoided if these measures had been implemented in Brazil,” concludes the UFPel epidemiologist.
Compound will be administered to 360 people aged 18 to 65
At the end of August, the Brazilian Health Regulatory Agency (ANVISA) authorized SpiNTec, the only COVID-19 vaccine candidate developed entirely in Brazil, to begin phase two trials on human beings. Phase two is the penultimate stage of clinical trials before a product can be approved for sale.
SpiNTec is one of three vaccine candidates for the novel coronavirus developed wholly or in part by Brazilians to reach the human testing phase (see Pesquisa FAPESP issue nº 321). It was created at the Vaccine Technology Center (CTVacinas) of the Federal University of Minas Gerais (UFMG), in partnership with the Oswaldo Cruz Foundation (FIOCRUZ) in Minas Gerais, and received investment from federal institutions, the Belo Horizonte government, and state representatives of Minas Gerais in Brazil’s House of Representatives.
In the second phase trials, the vaccine will be administered to around 360 volunteers aged 18 to 65, all healthy or with controlled chronic diseases, who have previously received doses of CoronaVac or the AstraZeneca vaccine and boosters of the Pfizer/BioNTech or AstraZeneca vaccine. “This is an important step towards registering the vaccine for public use,” immunologist Ricardo Gazzinelli, head of CTVacinas and a researcher at FIOCRUZ in Minas Gerais, told Agência FAPESP. The participants will be followed for one year.
The objective of the second phase is to continue assessing the safety of the vaccine candidate and identify any undesirable side-effects, in addition to evaluating immunological markers of efficacy.
Initial data from the phase one clinical trial, presented in June, indicated that SpiNTec is safe (meaning it does not cause serious health problems) and capable of inducing an immune response. In addition to stimulating the production of antibodies against the SARS-CoV-2 spike protein like most of the other currently available vaccines, the new formulation also enhances the activation of T lymphocytes, cells that fight cells infected by the virus. This double action could, in principle, make it effective against new variants. If all goes well, the last phase of testing should take place next year. “We already have FINEP funding approved for phase three, which will be released upon success of the current stage,” said Gazzinelli.
