COVID-19 Pandemic in the US

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Salient Points

Since the first US case of coronavirus disease 2019 (COVID-19) infection as identified in Washington State on January 20, 2020, more than 235 000 cases have been identified across the US in just over 2 months. As of April 2, there have been more than 5000 COVID-19–associated deaths in the US. With a global total now of more than 1 million cases, the US is now the country with the largest number of reported cases (as of writing of the article), comprising about one-fifth of all reported infections. With community transmission firmly established, the US epidemic enters the exponential growth phase in which the number of new cases is proportional to the existing number of cases.

The following article focuses on the state of the COVID-19 pandemic in the United States, it also gives insight on the following:

  • Case Fatality Rate
  • Global mortality rate is reported to be 4.7%
  • Among the first 140,904 cases in the US, 1.7% died
  • New clinical and epidemiological insights
  • As well as answers numerous questions regarding the testing procedures and patient post infection health conditions such as:
  1. Reinfection – It is unclear if it is true re-infection or if they tested falsely negative at time of discharge.
  2. Immunity duration – In a study that included 82 confirmed and 58 probable cases of COVID-19 from China, the median duration of IgM detection was 5 days, while IgG was detected at a median of 14 days after symptom onset.  Data from SARS-CoV-1 indicate that titers of IgG and neutralizing antibodies peaked at 4 months after infection, with a subsequent decline through at least 3 years after infection.
  3. Wearing of Masks
  4. Transmission of disease – Current evidence suggests that SARS-CoV-2 is primarily transmitted through droplets (particles 5-10 μm in size). Coughing, sneezing, and talking can lead to person to person transmission via droplets. They can land on the respiratory mucosa or conjunctiva of another person, usually within a distance of 6 ft (1.8 m) or even more. The droplets can also settle on stationary or movable objects and can be transferred to another person when they come in contact with these fomites. Survival of the virus on innate surfaces has been an important topic of discussion. While there is little data, the available evidence suggests that the virus can remain infectious on inanimate surfaces at room temperature for up to 9 days. This time is shorter at temperatures greater than 30C.
  5. Vaccinations

Detailed Summary

As of April 6th 2020, more than 235,000 cases have been identified in the US in just over 2 months. (Number is likely to much higher due to the challenges in expanding testing capacity)

Case Fatality Rate

  • Global mortality rate is reported to be 4.7% (10.8% in Italy and 0.7% in Germany)
  • Among the first 140,904 cases in the US, 1.7% died (Unreliable CFR due to varying denominator)

New Clinical and epidemiological insights

  • Positive PCR and Negative PCR

PCR remains the primary method of identifying SARS-CoV-2, although the sensitivity and specificity of diagnostic testing is unknown.

Note –

  1. Inadequate sample collection may reduce test sensitivity.
  2. 5 patients with CT findings compatible with COVID-19, but negative RT-PCR result for SARS-CoV-2, tested positive on subsequent testing.
  3. Proving that certain patients might require repeat testing with specimens collection from multiple sites in the Respiratory tract.
  4. Lower Respiratory tract samples are more sensitive.
  • Reinfection of patients

Reports from China and Japan have indicated that some patients with COVID-19 who were discharged after being tested negative were readmitted and later tested positive on RT-PCR.

It is unclear if it is true re-infection or if they tested falsely negative at time of discharge.

  • Duration of Immunity

In a study of 82 confirmed and 58 probable cases of COVID-19 in China, median duration of IgM detection was 5 days, while IgG was detected at a median of 14 days after symptom onset.

There is still no data on long term immune response.

Data from SARS-CoV-1 indicate that the titers of IgG and neutralising antibodies peaked at 4 months after infection, with a decline over 3 years after infection.

  • Wearing of masks by public

A fitted N95 Respirator is the preferred type of medical mask for health care workers.

They are recommended for symptomatic individuals and health care workers as well as among individuals at risk of transmission.

  • Transmission of SARS-CoV-2

Current evidence suggests its transmission primarily through droplets (particles 5-10 μm in size)

Droplets that land on respiratory mucosa or conjunctiva of another person, usually within a distance of 6ft (1.8m).

Transmission is also possible through fomites , i.e droplets that can settle on stationary or movable objects and thereby transferred to a person who comes in contact with these fomites.

  • Lifting of Social Distancing Measures

Social distancing according to studies suggest it can help reduce the overall number of infections and spread out cases over a longer period of time, giving health systems to better manage the surge in cases.

Long term social distancing however, may have detrimental effects on physical and mental health of individuals.

Changes to allow easing of restrictions

  • Aggressive program of testing to identify asymptotic and mild cases + proactive contact tracing and early isolation + quarantine of contacts.
  • Focus on reducing home based transmission.
  • Treatment that shortens the ICU stay by 20% to 30% can have a substantial benefit on the health system.
  • Availability of a Vaccine

As of publishing of the article, 3 vaccine candidates were in phase 1 of human trials

  1. A mRNA vaccine
  2. Other two being Adenovirus Vector based vaccines.
  3. Estimated timeline for availability of an initial vaccine is between early and mid 2021.

Reference Link : https://jamanetwork.com/journals/jama/fullarticle/2764366

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