Six months after
Covid-19 was declared a pandemic, this story is being republished as a
reminder of the many things scientists have learned about the disease
and how it spreads.
We’re in a terrifying
and confusing pandemic, with new and sometimes conflicting information
about Covid-19 emerging all the time. In the early days, a lot of public
health advice was based on what we knew about previous disease
outbreaks. But this new coronavirus behaves
in unexpected ways, and it’s hard to keep up. What’s more, people tend
to remember the first things they learn about a new subject, a
phenomenon called "anchoring bias," and it’s psychologically challenging
to replace old information with new knowledge.
Here are nine of the most important things we’ve learned about
SARS-CoV-2 in the past seven months and why we didn’t fully understand
or appreciate them at first.
Outbreaks of Covid-19
can happen anywhere. There was a lot of wishful thinking (as in: it’s those other people’s problem) in the first months of the
pandemic: Chinese people got it because of where they buy their
groceries. Italian people got it because they
greet each other with kisses on the cheeks. People on cruise ships got
it because of the buffets. People in nursing homes got it because they
are frail. People in New York got it because the city is crowded. Now we
know that outbreaks can happen in urban areas, rural areas, suburbs and any culture around the world.
Covid-19 can sicken and
kill anyone. The first victims of the pandemic were disproportionately
older or had existing health conditions. Age and frailty are still risk
factors for serious disease and death, but we now know the disease can
kill young and healthy people. It can kill young adults. It can kill teenagers. It can kill children.
Contaminated surfaces
are not the main danger. Early on, public health experts advised people
to wash their hands frequently (while singing “Happy Birthday” twice),
disinfect surfaces and avoid touching their face. This was based on
studies of how other diseases spread, such as norovirus and viruses that
cause common cold. It's still a good idea to wash your hands regularly (
and avoid handshakes), but now we know that surfaces aren't the main
vector for SARS-CoV-2.
It is in the air. At
first, experts thought the virus was spread primarily through globs of
mucus and saliva expelled when people cough or sneeze. They thought
these droplets were heavy enough to drop out of the air fairly quickly.
Based on early cases of hospital spread,
the virus seemed to be aerosolized—that is, lofted into the air in
particles small enough to float—only by certain medical procedures such
as placing someone on a ventilator. But we now know that the virus is
expelled in a range of droplet sizes, with some particles small enough
to persist in the air, especially in indoor, poorly ventilated spaces.
Many people are
infectious without being sick. Other respiratory diseases make people
cough and sneeze. The original SARS outbreak made people so sick, so
quickly, that most of them went to the hospital. Temperature checks and
telling sick people to stay home can stop symptomatic diseases from spreading,and in the first months
of the pandemic, many countries started screening people at their
borders to detect these cases. But the biggest challenge for stopping
SARS-CoV-2 is that many apparently healthy people spread the disease
without symptoms or before symptoms start, simply through talking and breathing.
Warm summer weather
will not stop the virus. Influenza is a seasonal respiratory disease
that peaks in the winter, and some experts hoped the spread of Covid-19
would show a similar pattern and slow in the Northern Hemisphere during
the spring and summer. Now, we know that people's behaviour, regardless
of season, is the strongest predictor of whether the disease will
spread.
Masks work. When the
pandemic began, experts worried that mass mask-buying could exacerbate
shortages of personal protective equipment for health care workers and
others who needed them. They also warned that masks might make people
complacent about social distancing, and that cloth or paper masks ( unlike N95 surgical masks) can’t stop the smallest
aerosolized viral particles. Now we know that masks can greatly reduce
the amount of virus that people expel into the air while speaking, and
that masks protect people who are wearing them—not perfectly, but enough
to reduce transmission of the disease.
Racism, not race, is a
risk factor. The pandemic should put an end to the common misconception
that race, a social construct, is a biological explanation for health
disparities. Covid-19 has disproportionately killed people of color in
the United States. This is not because of genetic differences but because of systemic
racism that has isolated and impoverished many Native American people
and made Black and Latinx people more likely to have “essential” jobs
that expose them to infection, a greater burden of stress and less
access to high-quality healthcare.
Misinformation kills.
The president of the United States, other politicians, anti-vaccine
activists, and members of the right-wing media, to their everlasting
shame, have used the pandemic to stoke racism, spread misinformation and
amplify conspiracy theories. Their followers have threatened health officials,
including Tony Fauci
and his family; refused to wear masks; refused to cooperate with contact
tracers; and rejected proven basic public health advice about social
distancing. Representative Louie Gohmert, who refused to wear a mask in
the Capitol and reportedly discouraged his staff and interns from wearing masks, tested positive for SARS-CoV-2 and is
being treated with hydroxychloroquine, a drug that Trump has endorsed
but that has failed in clinical trials. Trump supporter Herman Cain died
of Covid-19 on July 30, weeks after attending a rally in Tulsa without a
mask. Calls to poison-control
centers spiked after Trump speculated that injecting or ingesting
disinfectants could protect against the coronavirus. Early evidence
suggests people who watched Fox News were more likely to downplay the
pandemic, worsening the spread .
The most important
public health measure during a pandemic of a disease with no cure or
vaccine—as many countries around the world that have controlled the
virus have shown—is to help experts share clear, trustworthy, accurate,
actionable information based on the best evidence. Spreading lies has spread this disease.