Can COVID-19 recur

The WHO confirmed that it is investigating reports of some recovered coronavirus patients who have tested positive for the illness after initially testing negative.

Why WHO is investigating reinfections

The move has come as a response to a report from South Korea that 91 patients who had been cleared of COVID-19 and were being prepared for discharge tested positive again. Officials have stated that rather than being reinfected, this may be a reactivation of coronavirus.

What is current WHO discharge policy

The WHO’s clinical management guidelines state that patients can be discharged from the hospital after two negative coronavirus test results at least 24 hours apart.

Has any country seen > 2000 deaths in a day

11^th April: US became the first country to record over 2,000 coronavirus deaths in 24 hours.

 What are Serology-based tests for COVID-19

Serology testing for SARS-CoV-2 is in increased demand to better quantify the number of cases of COVID-19, including the asymptomatic and recovered ones. These are blood-based tests that help identify whether people have been exposed to a particular pathogen by looking at their immune response.

How do they differ from RT-PCR test

The RT-PCR tests currently being used across the globe to diagnose cases of COVID-19 can only point to the presence of viral material during infection and do not indicate if a person was infected and subsequently recovered.

Why do we need antibodies test

 These tests provide greater detail into the prevalence of a disease in a population by identifying individuals who have developed antibodies to the virus.

What are rapid diagnostic test (RDT)

This is a qualitative (positive or negative) lateral flow assay. It is small, portable, and can be used at point of care (POC). The tests may use blood samples from a finger prick, saliva samples, or nasal swab fluids. RDTs are usually similar to pregnancy tests. The test shows colored lines to indicate positive or negative results.  

In the COVID-19 scenario, these tests most frequently identify patient antibodies (IgG and IgM), or viral antigen. In some cases, it can be beneficial to measure baseline (before infection) IgG and IgM titers.

What are Enzyme-linked immunosorbent assay (ELISA) tests

This is a qualitative or quantitative test; generally a lab-based test. These tests usually use whole blood, plasma, or serum samples. A plate is coated with a viral protein of interest, such as Spike protein. Patient samples are incubated with the protein, and if the patient has antibodies to the viral protein, they bind together. The antibody-protein complex can then be detected with another wash of antibodies that produce a color or fluorescentbased readout.

 In the context of COVID-19, these tests identify patient antibodies (IgG and IgM).

What are Neutralization assays

 This test relies on patient antibodies to prevent viral infection of cells in a lab setting. Neutralization assays can identify if a patient has antibodies that are active and effective against the virus, even if they have already cleared the infection. These tests make use of whole blood, serum, or plasma samples. Neutralization assays depend on cell culture, a lab-based method of culturing cells that allow SARS-CoV-2 growth (like VeroE6 cells). When virus and cells are grown with decreasing concentrations of patient antibodies, it is possible to visualize and quantify how many antibodies in the patient serum can block virus replication. This blocking action may occur through the antibody binding to an important cell entry protein on the virus.

Can RT-PCR be false negative

Negative RT-PCR tests on oropharyngeal swabs despite CT findings suggestive of viral pneumonia have been reported in some patients who ultimately tested positive for SARS-CoV-2 [Radiology. 2020]

Can RT-PCR be negative and IgM positive

Serologic tests should be able to identify patients who have either current or previous infection but a negative PCR test.

A study including 58 patients with clinical, radiographic, and epidemiologic features suggestive of COVID-19 but with negative SARS-CoV-2 PCR testing, noted that an IgM enzyme-linked immunosorbent assay (ELISA) was positive in 93% (and was negative when tested separately on plasma specimens that predated the COVID-19 outbreak) [Clin Infect Dis. 2020]

Can we go for viral culture

For safety reasons, specimens from a patient with suspected or documented COVID-19 should not be submitted for viral culture.

 CMAAO CORONAVIRUS FACTS and MYTH BUSTER 46

Is there a link with long-term pollution and COVID-19 mortality

A new study sheds light on the link between COVID-19 health impacts and air pollution.

Dr. Francesca Dominici, author and Director of the Data Science Initiative at Harvard’s T.H. Chan School of Public Health has stated that people living in counties in the US with a higher level of air pollution over the past 15-17 years have recorded a considerably higher COVID-19 mortality rate. One unit increase in long-term average exposure to fine particulate matter is associated with a 15% increase in COVID-19 mortality rate on average, revealed the analysis.

A one unit increase in long-term exposure to PM2.5 leads to a 15% increase in COVID-19 mortality rate with an enormity that is 20 times that of PM2.5 and all-cause mortality (which is 0.7%).

In the Medicare study [Di et al, 2017], a one unit increase in long-term exposure to PM2.5 was associated with a 0.7% increase in all-cause mortality. In this study, that one unit is associated with a 15% increase in COVID-19 mortality. Therefore, the relationship between PM2.5 and COVID mortality is 20 times stronger than the relationship between PM2.5 and all-cause mortality.

What is the mortality rate in India

3.4%

Can this be linked to high pollution rates in the air

One can only postulate

When will social distancing end

When the following conditions are fufilled:

• The number of new infections start going down over time
• We have a huge ability to diagnose cases through testing
• Proper equipment, such as masks and other personal protective equipment, are fully available for doctors, nurses, and hospital staff so that they can care for the sick safely and effectively
• Hospitals have all the equipment they need like beds, ventilators, and are fully prepared for new cases
• A strong public health infrastructure is there to identify new cases and trace contacts in order to prevent spread and contain new outbreaks

Are there phases of social distancing

 Yes, there are four phases

What is phase 1

Social distancing is the Phase One. It helps us gain some time to accomplish the conditions described above.

What is phase 2

Phase 2: If cases do not rise over a 2-week period.

What are the components of phase 2

In Phase 2, businesses and schools are allowed to reopen with appropriate physical distancing measures and increasing disinfecting and cleaning of public spaces. Large gatherings would need to be limited. High risk people such as the elderly and those with underlying health problems may need to limit time spent outside the home until there are confirmed treatments available. If, at any time, cases rise in an unmanageable way, there will be a need to go back to social distancing.

What is phase 3

Phase 3: This refers to a time when almost all physical distancing restrictions can be lifted. This would be guided by whether or not our country has a strong COVID-19 surveillance infrastructure to eliminate any new cases quickly, readily available drug treatments, and potentially a safe and effective vaccine.

What is phase 4

Phase 4: This is a time when all of the lessons learned from this pandemic are put to use to expand public health and healthcare infrastructure, besides developing strong emergency preparedness plans to refurbish our readiness. This will help protect us from future threats without the same severe conditions we have had to face during this pandemic.

How to tackle future pandemics

Aggressively implementing Phase Four would help us respond to future threats in a way similar to how South Korea responded to COVID-19.

What is the timeline for each phase

The timeline to move from one stage to another is not clear. Some stages could take weeks, while others may take months to years.

What is happening in Italy

It is being estimated that they will have virtually eliminated new COVID-19 cases by May 16, 10 weeks after the entire country went into lockdown.

They reached their peak 4 weeks after lockdown and then show a sustained decline in the number of cases. It’s still not clear when will the restrictions be eased down there.

What is circuit breaker

It is a term used by Singapore for lockdown.

In Singapore, on April 3, Prime Minister Lee Hsien Loong announced significantly stricter measures to curb the COVID-19 outbreak. He likened this to a “circuit breaker”.

What is Janta Karphew

India used this term for lockdown on 22^nd March.

What is Movement Control Order (MCO)

This is a term used by Malaysia for lockdown

What is Shelter-in-Place and Stay-at-Home Orders

These are the US terms for lockdown

Dr KK Aggarwal

President, CMAAO