5 things we learned from COVID in three years

Three years ago on March 11, 2020, Tedros Adhanom Ghebreyesus, director-general of the World Health Organization (WHO), announced that the coronavirus that causes COVID was spreading globally and that the outbreak was officially a pandemic. At the time, there were more than 118,000 confirmed cases of COVID and 4,291 official deaths.

“In the coming days and weeks,” Ghebreyesus told a news conference at the time, “we expect to see the number of cases, the number of deaths and the number of countries affected increase even more.”

Three years later, the WHO has recorded more than 6.8 million deaths from COVID, although studies of global excess mortality, or deaths above and beyond the expected amount at a given time, suggest the actual number is more than double of this amount. In the US, there have been about 1.1 million deaths from COVID, according to the US Centers for Disease Control and Prevention. Long-term COVID, which occurs when people develop lingering or new symptoms even after they recover from the initial infection, has also emerged as a threat that remains mysterious, although doctors are increasingly exploring possible causes and treatments.

The populations most at risk now are people with preexisting chronic conditions whose health is fragile and for whom hospitalization is a frequent occurrence, says Jeremy Faust, an emergency medicine physician at Brigham and Women’s Hospital in Boston. COVID is another factor that can push these individuals toward death. As a result, the pandemic is still causing excess mortality in the U.S. Mortality fluctuates from month to month, but was about 10 percent higher in November 2022 than it was before the pandemic, Faust says.

If March 2020 was like a flood, says Faust, today the world is no longer drowning. But the new normal is a little worse than before, he says: “Sea level is just higher,” adds Faust.

There’s a greater awareness now that a pandemic virus can disrupt societies, says Amesh Adalja, an infectious disease physician and senior fellow at the Johns Hopkins Center for Health Security. However, this awareness does not always translate into action. “It’s still not a high priority from policymakers, and there are really big questions about how the U.S. might respond” to a future pandemic, Adalja says. Public health mistakes in the 2022-2023 monkeypox outbreak, ranging from poor access to testing to clumsy vaccine distribution, echoed those made at the start of the COVID pandemic, he says.

“Until [infectious disease] prioritized in a way that national security is, I don’t think you’re going to see full resilience,” says Adalja. “What you need is a proactive, consistent approach that doesn’t just last one election cycle.”

Despite the challenges of preparing to build, we have learned some hard-won lessons about SARS-CoV-2, the coronavirus that causes COVID, that could inform our approach to future pandemics—and public health more generally.

mRNA vaccines are safe, potent and effective

One of the clear successes of the response to the COVID pandemic has been the rapid development of effective vaccines.

The pandemic was the first large-scale test for mRNA vaccine technology, which proved safe and effective against severe disease and death, even as the virus evolved to form new variants. A recent analysis by the Commonwealth Fund, an independent research group focused on health care issues, found that in the two years after vaccines were introduced in the US, vaccines prevented about 18 million hospitalizations and three million deaths.

Masks work

Masks and mask mandates became a political flashpoint during the pandemic, but evidence shows they are slowing the spread of COVID and other respiratory diseases. For example, according to the CDC, at least 10 studies as of late 2021 found that after local authorities implemented universal coverage mandates, infection rates dropped.

The best protection comes from high-quality N95 and KN95 masks. A major publication in February 2022 at the CDC’s Morbidity and Mortality Weekly Report compared people who had tested positive for COVID and people who had not and assessed their mask-wearing habits. Among 534 participants who reported their mask type, consistent use of a cloth mask reduced the odds of a positive test by 56%, use of a surgical mask reduced the odds by 66%, and use of an N95 or KN95 reduced the odds by 83%. Masks are most effective when sealed well, worn properly, and layered with other precautions.

Indoor air quality matters

In early 2020, no one knew how the virus spread, and the CDC and other health agencies around the world were sending mixed messages. Hand sanitizer became a national obsession. People swept up their groceries or left them overnight in their garage.

But research would soon confirm that the virus spreads mainly through the air and not through surfaces. This realization has sparked interest in improving indoor air quality through both ventilation (removing outside air) and filtration (cleaning the air of particles and pathogens). Research has found that continuous high-efficiency particulate air (HEPA) filtration can remove the vast majority of airborne COVID particles and dramatically reduce exposure. And the effect is not limited to COVID: filtering also removes other viral particles such as influenza from the air.

Sewage monitoring is useful for COVID and other diseases

The idea to track the spread of the virus through sewage first emerged in early 2020 and has now become a national program. Sewage has given up to several weeks’ warning of upcoming infections because people begin shedding SARS-CoV-2 before they experience symptoms or seek medical attention. Wastewater monitoring is now integrated with other disease monitoring. Scientists have used wastewater to monitor increases in viruses such as RSV and influenza.

Genomic surveillance is key to monitoring the evolution of the virus

SARS-CoV-2 does not remain static. Over the past three years, variants such as Delta, which caused outbreaks and severe disease in 2021, and the highly contagious Omicron, which spread rapidly in late 2021 and is still the dominant variant worldwide, have changed the course of the pandemic. . Variants wax and wane in dominance as they compete with each other to spread through the population, although Omicron subvariants currently make up 99.9% of all cases.

Countries and health services around the world have now established genomic surveillance to track new variants. Strong surveillance is key to responding to new pandemic twists and turns, according to Jarbas Barbosa, director of the Pan American Health Organization, which coordinates a regional genomic surveillance network in the Americas. The challenge is to maintain interest in these efforts even as the acute phase of the pandemic subsides.

“As we learn to live with this virus, countries must … maintain and continue to strengthen surveillance,” Barbosa said at a March 9 media briefing. “The risk of new variants is real.”

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