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What do we now know about COVID?
SARS-CoV-2 is a respiratory virus that has an incubation period of up to 14 days (most individuals have symptoms in 5 days post exposure), and causes a varied number of symptoms including but not exclusively;
- cough (50%)
- fever (43%)
- muscle aches (36%)
- headache (34%)
- shortness of breath (24%)
- sore throat (20%)
- diarrhea (19%), nausea, vomiting (19%)
- loss of taste, abdominal pain and runny nose (less than 10%).
Individuals of any age can acquire COVID-19. Most COVID positive individuals have mild or moderate disease with progression of symptoms over a week, and recover fully.
Adults of middle age and older are most commonly severely affected, and older adults are more likely to have severe disease. However, severe disease is not limited to older individuals.
Severe complications (15-20% of those infected) do occur usually after 7 days of symptoms and are more commonly seen in older individuals with diabetes, cardiovascular disease (heart disease, vascular disease, high blood pressure), chronic kidney disease, pre-existing lung conditions and smokers, obesity, and immunosuppressed individuals.
Severe complications are associated with an intense inflammatory response and elevated inflammatory markers in the body, low oxygen levels, pneumonia, respiratory distress (needing ventilation intervention), cardiac injury, irregular cardiac rhythms, clotting abnormalities resulting in clots to the lungs and brain, kidney problems, severely depressed white cells called lymphocytes (they fight viral infections). An intense immune dysfunction exists either as a reduction or excessive response to fighting disease. The severity of these findings determines outcome.
What are emerging questions and challenges?
Males and COVID
Males have comprised a disproportionately high number of deaths in cohorts from China, Italy, and the United States. Read more about this here, here and here.
Asymptomatic Infection
Information on the natural history of asymptomatic infection with COVID-19 remains scarce. In a study of 96 patients, the majority of asymptomatically infected persons remained asymptomatic throughout the course of the infection. The time to the resolution of infection increased with increasing age.
COVID in Stool
12% of patients with COVID-19 will manifest GI symptoms, however, SARS-CoV-2 shedding was observed in 40.5% of patients with confirmed infection.
What are the implications for infection control for COVID patients and what measures are needed to protect their health providers ?
Accuracy of testing
Sensitivity of COVID testing is approximately 70%. Using statistical analysis, 23% of individuals with negative tests have a probability of an infection. Even with more sensitive testing, infection cannot be ruled out. If a person has typical symptoms and exposure risk, repeated testing may be required and clinical judgement is mandatory in each case. At a population level, contact tracking, physical distancing measures and hand washing need to remain as treatment measures.
COVID Treatment
Dexamethasone has been shown to reduce mortality in COVID patients. This has caused a lot of excitement in the medical community but further review of the research needed. Also, concern about the data analysis has begun.
MIlken Institute (Faster Cures) is currently tracking the development of treatment and vaccine for Coronavirus. Currently 254 treatments and 172 vaccine are being worked on by private industry, academia, drug developers etc.
What is the state of research on COVID treatment and vaccine development?
Treatment Research Areas
- Antibodies to treat disease - both naturally occurring (from patients previously exposed to COVID) and antibodies that are being attached to molecules in the body that can be used to treat disease.
- Antiviral drugs. These stop the virus from making copies of itself.
- Cell therapy. Cells are taken from the patient or a donor to help the immune system of the COVID patient work better.
- Blood purification devices to remove excess proteins (present as a result of intense inflammation) that cause organ failure.
- Scanning for compounds already in use for other purposes (for example steroid etc) that may be able to be repurposed to treat the overreaction of the immune system.
- DNA base therapies - insertion of altered viral genes into DNA carriers (plasmids) into vaccinated people. The cells pick up the DNA and make viral particles that the body sees as foreign and mounts an immune response to. Other viral research uses inactivated live virus (like measles mumps vaccine ) or weakened virus, or a protein particle of the virus (like hepatitis and shingles vaccines) to trigger an immune response.
- Vaccines
Vaccine Clinical Trial Stages:
- Phase 1 safety trials: Scientists give the vaccine to a small number of people to test safety and dosage as well as to confirm that it stimulates the immune system.
- Phase 2 expanded trials: Scientists give the vaccine to hundreds of people split into groups, such as children and the elderly, to see if the vaccine acts differently in them. These trials further test the vaccine’s safety and ability to stimulate the immune system.
- Phase 3 efficacy trial: Scientists give the vaccine to thousands of people and wait to see how many become infected, compared with volunteers who received a placebo. These trials can determine if the vaccine protects against the coronavirus.
- Approval: Each country reviews the trial results and decides whether to approve the vaccine or not. In a pandemic emergency approval may be given to use a vaccine before formal approval.
The WHO has launched an international clinical trial called Solidarity to help find an effective treatment for COVID-19. Its aim is to reduce the time taken by clinical trials by 80%. By using single large trials, worldwide comparisons of unproven treatments can be evaluated. The greater the number of participating countries, companies, etc. the faster the results are generated.
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