Breakout in the USA: Patient Zero and Party Zero
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| Drive-through station Westport CT, conducted by Murphy Medical Associates Source: The Hour |
Jan 13-20 First cases
The first identified case of the novel coronavirus in the USA was a 35 year old man who returned
on January 15 to Washington State from Wuhan in China. He attended hospital after four days of a
dry cough, fever, nausea and vomiting. His swabs on January 20 showed SARS-CoV-2.
After 5 days in hospital, pneumonia appeared in the lower lobe of one lung.
Supplemental oxygen was delivered. By the next day he developed streaky opacity
in the lung, but 3 days later his condition improved. He was not known to have spread
the infection. Dr Helen Chu, in charge of the research project, was suspicious but could not get permission to engage in community testing. After a month she arranged it herself, and suddenly a large number of what appear to be descendant cases were identified in the area.
The first person-to-person transmission in the USA was from a
lady in her 60s who returned to Illinois from Wuhan with her husband on January
13. She had fever, fatigue and cough and was hospitalised with pneumonia on
January 19. Her husband, who had not travelled to China, already had chronic
obstructive pulmonary disease. He was admitted to hospital on January 27 and
the next day tested positive for CV. Both patients improved and were discharged
home.
An intensive epidemiological investigation was undertaken. Some
372 contacts of the patients were identified, of which 195 were health care
personnel. About a third had medium-risk exposures. Although quite a number
developed a cough, none were infected.
Following these cases, the Center for Disease Control (CDC),
the primary body for disease control in the USA, issued a summary on February 25 of the situation, more of a
hypothetical nature, noting
Widespread transmission of COVID-19 in the United States would translate into large numbers of people needing medical care at the same time. Schools, child care centers, workplaces, and other places for mass gatherings may experience more absenteeism. Public health and health care systems may become overloaded, with elevated rates of hospitalizations and deaths.
Party Zero: How a Soirée in Connecticut Became a ‘Super Spreader’
At the opposite extreme, when 50-100 people gathered on 5 March from
all over the country for a ‘gilded age’ soirée in upmarket Westport Connecticut, at
least a third of those present were infected. They then scattered across the
region and the world, taking the coronavirus with them and seeding infections
along the way. Three days later, one of the guests reported “pain, tightness
and heaviness like someone was standing on my chest,” Four days later she was
diagnosed with COVID-19.
A coronavirus information forum was convened by
health officials at the local library . The director stated there were no cases,
there were no testing kits, but the risk was low. A businessman from Johannesburg
who had attended fell ill on his flight home and tested positive on March 11.
Becoming alarmed, the Health District conducted a drive-through testing facility for party guests teh next day. Over half were infected. Once the extent of the subsequent contacts of the attendees was realised, the city shifted on March 16 from a contact-tracing model to a containment model — placing restrictions on further public gatherings, businesses and public parks. Around this time, a number of states in the USA also ordered lockdowns of various degrees of severity.
Becoming alarmed, the Health District conducted a drive-through testing facility for party guests teh next day. Over half were infected. Once the extent of the subsequent contacts of the attendees was realised, the city shifted on March 16 from a contact-tracing model to a containment model — placing restrictions on further public gatherings, businesses and public parks. Around this time, a number of states in the USA also ordered lockdowns of various degrees of severity.
On March 23 and 24, the ‘superspreader’ party was reported across
the world’s media.
As in Australia, many of the New York and New England cases have now been identified as separate strains from the Wuhan strain in Washington state, derived mostly from Europe.
As in Australia, many of the New York and New England cases have now been identified as separate strains from the Wuhan strain in Washington state, derived mostly from Europe.
How are superspreaders doing it?
Most advice ofn COVID-19 has presumed it is spread mostly in large droplets that are coughed or sneezed then fall to the ground. This has led to the current 'social distancing' advice of maintaining a 1m or 2m separation from others.
However, another case study from Washington State suggests that the superspreading is done through aerosols (fine particles) which can carry a considerable distance, can pass form talking and can remain suspended in the air, so that passers-by may walk into a Covid cloud.
A choir group in Skagit, Washington, met for a two-hour practice in early March. No one was symptomatic, so singers weren’t coughing or sneezing out infected droplets. Everyone kept their distance. However, 45 people became infected with COVID-19 and at least two people died from the virus. That suggested the viral particles were shed as aerosols by someone, before being inhaled or otherwise acquired by other choir members.
A choir group in Skagit, Washington, met for a two-hour practice in early March. No one was symptomatic, so singers weren’t coughing or sneezing out infected droplets. Everyone kept their distance. However, 45 people became infected with COVID-19 and at least two people died from the virus. That suggested the viral particles were shed as aerosols by someone, before being inhaled or otherwise acquired by other choir members.
Conclusion - institutional failure?
Two questions emerge from these incidents.
The first question concerns transmission. Why did one pair of patients with a large number of contacts not transfer the disease to anyone
else over a month, whereas in a week Patient Zero established the disease in the community without it becoming evident. Party Zero gave the disease to many of those present in a few
hours, and so did the choir group. The main feature here was the group setting, and it is not surprising
that early distancing requirements sought to discourage these large gatherings.
The second and more important question is why did the
disease get away from a national corps of well-informed fully competent health
professionals, and why was nothing done to support them with wide testing, to quarantine entry or
to execute containment until it was far too late? In most states, despite the huge number of recorded cases, containment is at Level 2 and only San Francisco and New York have tough Level 3 shutdowns like most of Europe and Australia.
In each of these examples, medical personnel and local officials acted promptly and professionally to do their jobs, to contain any problem and report it upstairs - but it was not enough.
In each of these examples, medical personnel and local officials acted promptly and professionally to do their jobs, to contain any problem and report it upstairs - but it was not enough.
The CDC was fully informed
yet it also seemed powerless to conduct even the limited preliminary
quarantining that might have prevented what might well be more than one hundred thousand deaths.
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Quite a bit more has emerged about the early history of the virus in the USA.
The tissue of a woman who died in Santa Clara county California has shown positive for the virus. She had not travelled outside the USA, so it was community transfer. She picked it up before Jan 25 so the timing was similar to Patient Zero.
It is guesswork about how many were infected in January - probably less than 100. Between 20 and 50 infected people arrived in the US from China or other countries in January.
Antibody tests can not help much - there is a 1% error rate so a considerably higher proportion of the population would need to be infected before statistically significant results were produced.
Although we have suggested that a higher proportion of the American public might already be infected, there is no good proof for this. The proportion tested in the US who were confirmed positive stuck around 18% through several weeks in late April, and has now fallen to 15% as tests move ahead of new cases at last. However this really just confirms the success rate of doctors in picking who should be tested - among contacts and people with similar symptoms, not who actually has it.
The number confirmed infected in the USA is 3.9 per thousand. The general assumption has been that the number of symptomless is about the same as the number confirmed, so on that basis less than 1% of the population would have had the disease.
The success rate of testing in New York and New Jersey has been very much higher, at about 42% to 50% - but this might also imply that only 3% of the population have had the disease so far. Even allowing for children , the country is still a very long way from any kind of herd immunity based on this. If coronavirus does typically kill 1%, then we would be eventually looking at something like 1.5 million deaths, 20 times the 77,000 we currently have - still a very long way to go.
Of course all this analysis depends on the ratio of symptomless infected to total infected - a crucial parameter. It is surprising so little effort has been put into calculating it.
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Addendum May 11 - What is now known
Quite a bit more has emerged about the early history of the virus in the USA.
The tissue of a woman who died in Santa Clara county California has shown positive for the virus. She had not travelled outside the USA, so it was community transfer. She picked it up before Jan 25 so the timing was similar to Patient Zero.
It is guesswork about how many were infected in January - probably less than 100. Between 20 and 50 infected people arrived in the US from China or other countries in January.
Antibody tests can not help much - there is a 1% error rate so a considerably higher proportion of the population would need to be infected before statistically significant results were produced.
Although we have suggested that a higher proportion of the American public might already be infected, there is no good proof for this. The proportion tested in the US who were confirmed positive stuck around 18% through several weeks in late April, and has now fallen to 15% as tests move ahead of new cases at last. However this really just confirms the success rate of doctors in picking who should be tested - among contacts and people with similar symptoms, not who actually has it.
The number confirmed infected in the USA is 3.9 per thousand. The general assumption has been that the number of symptomless is about the same as the number confirmed, so on that basis less than 1% of the population would have had the disease.
The success rate of testing in New York and New Jersey has been very much higher, at about 42% to 50% - but this might also imply that only 3% of the population have had the disease so far. Even allowing for children , the country is still a very long way from any kind of herd immunity based on this. If coronavirus does typically kill 1%, then we would be eventually looking at something like 1.5 million deaths, 20 times the 77,000 we currently have - still a very long way to go.
Of course all this analysis depends on the ratio of symptomless infected to total infected - a crucial parameter. It is surprising so little effort has been put into calculating it.
<Return to Index>
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