Fact check: Knowns and unknowns about COVID-19

It may feel like the coronavirus crisis has lasted an eon, but in reality, the COVID-19 pandemic has been with us for just over seven months and much remains to be discovered about the virus.

Much of what we thought we knew about the novel coronavirus early in the year has been challenged and changed by the ever-evolving science around the disease.

Considering the COVID-19 pandemic hasn’t yet marked its first birthday, scientists already know quite a bit about the virus, as vaccine and treatment research accelerates at an unprecedented pace.

For everything we currently know about the novel coronavirus, however, many more aspects remain to be revealed and understood.

To date, more than 13 million COVID-19 cases have been confirmed worldwide and more than half a million deaths have been attributed to the virus.

Below are some of the areas where COVID-19 knowledge has evolved or where unknowns remain.

What are the symptoms of COVID-19?

The earliest descriptions of COVID-19 symptoms focussed on fever, shortness of breath or cough. We now know that the novel coronavirus is associated with a variety of other symptoms. The US Centers for Disease Control and Prevention has expanded the list to include fever or chills, cough, shortness of breath or difficult breathing, fatigue, muscle or body aches, headache, loss of taste or smell, sore throat, congestion or runny nose, nausea or vomiting, and diarrhoea.

The Cayman Islands Government lists coughing, fever, tiredness, breathing difficulties, and loss of taste and smell.

“These symptoms are usually mild and begin gradually but commonly occur within 1-10 days after a person has been exposed,” CIG writes.

“Some people become infected but don’t develop any symptoms and don’t feel unwell. Around one out of every six people who gets COVID-19 becomes seriously ill and develops difficulty breathing.”

The CDC recommends seeking medical attention if symptoms include trouble breathing, persistent pain or pressure in the chest, confusion, inability to stay awake, or bluish lips or face.

Click to enlarge.

Can COVID-19 be spread by air?

Whether COVID-19 transmission can be airborne has been a source of international debate and disagreement. While droplets have been identified as a main source of spread, some scientists are also concerned the virus may have potential to linger in the air and spread over greater distances.

In an open letter to the World Health Organization on 6 July, 239 scientists highlighted the potential for airborne spread.

“We appeal to the medical community and to the relevant national and international bodies to recognize the potential for airborne spread of COVID-19,” the letter states.

“There is significant potential for inhalation exposure to viruses in microscopic respiratory droplets (microdroplets) at short to medium distances (up to several meters, or room scale), and we are advocating for the use of preventive measures to mitigate this route of airborne transmission.”

The World Health Organization states that current evidence indicates the primary means of COVID-19 transmission occurs through respiratory droplets and that in analysis of more than 75,000 cases in China, airborne transmission was not reported. WHO recommends interpreting recent findings about COVID-19 aerosolisation carefully.

The first coronavirus antibody test is carried out at Cayman Islands Hospital in June. – Photo: Taneos Ramsay

How effective are coronavirus antibodies in preventing reinfection?

Testing for coronavirus antibodies, now available at several healthcare facilities in Cayman, can provide a clue as to how many individuals have been previously infected with the virus. It can also help doctors identify candidates for blood donations to treat hospitalised COVID-19 patients.

Coronavirus antibodies may not last for long in individuals who have recovered from COVID-19, however, and research suggests people may be vulnerable to repeat infections, as occurs with the common cold.

Cayman’s Chief Medical Officer Dr. John Lee has said previously that much remains to be known about COVID-19 antibodies.

“We’re still learning about the science, what the antibody test means, and its implications to the clinical management of the disease,” Lee said at press conference in June.

The Guardian first reported on 12 July about a King’s College London study that found a steep decline in antibodies within months of recovery.

More than 90 patients were analysed for the study. Scientists found a peak in antibodies three weeks after the onset of symptoms, followed by a rapid decline. After three months, only 17% of those studied retained the same antibody potency.

The study casts doubt on hopes of developing ‘herd immunity’ or of approving ‘immunity passports’ for individuals who have been previously infected.

Professor Jonathan Heeney, a virologist at the University of Cambridge, told The Guardian that ‘herd immunity’ is a dangerous concept.

“Some of the public, especially the youth, have become somewhat cavalier about getting infected, thinking that they would contribute to herd immunity,” he said. “Not only will they place themselves at risk, and others, by getting infected, and losing immunity, they may even put themselves at greater risk of more severe lung disease if they get infected again in the years to come.”

Are face masks effective in preventing infection?

Widespread use of face masks in indoor, public spaces has now become the recommendation made by most governments and health agencies, but this was not always the case. Since March, the number of countries requiring mask wearing has grown from 70 to 120, according to University of Oxford.

In the Cayman Islands, people over age 2 are required to wear face masks or coverings inside enclosed or indoor public spaces, inside taxis and buses, or when waiting for public transport in a semi-enclosed space.

Concerns about global N95 shortages early on in the pandemic led some health agencies to recommend that only sick individuals wear a mask to prevent the spread of coronavirus. Most governments now recognise, however, that general use of face coverings – whether that be an N95 mask or a homemade mask with a filter – helps control viral spread and prevents asymptomatic carriers from unknowingly infecting others.

The efficacy of face masks in preventing viral spread has also been demonstrated through multiple scientific studies.

A study released in June by Oxford found face coverings and homemade masks were effective in preventing virus transmission when the masks were made of optimal materials, such as high-grade cotton or were multilayer. Social behaviours, public understanding and consistent public messaging were noted as influencing factors in the effectiveness of face mask use across communities.

“The public is confused about wearing face masks and coverings because they have heard the scientific evidence is inconclusive and advice from the WHO and others has changed. People also feared they might be competing for scarce PPE resources and they need clear advice on what to wear, when to wear them and how to wear them,” said Professor Melinda Mills, author of the Oxford study.

“The evidence is clear that people should wear masks to reduce virus transmission and protect themselves, with most countries recommending the public to wear them. Yet clear policy recommendations that the public should broadly wear them has been unclear and inconsistent in some countries such as England.”

The CDC explains that face masks help the wearer protect others.

“A cloth face covering may not protect the wearer, but it may keep the wearer from spreading the virus to others,” the CDC states.

“Cloth face coverings are most likely to reduce the spread of COVID-19 when they are widely used by people in public settings. The spread of COVID-19 can be reduced when cloth face coverings are used along with other preventive measures, including social distancing, frequent hand washing, and cleaning and disinfecting frequently touched surfaces.”

Click to enlarge.

How close are we to having a COVID-19 vaccine?

Laboratories around the world are racing to find a vaccine for COVID-19 and while a publicly available vaccine will take time to test and approve, there have been some promising study results.

One experimental vaccine, developed by US government scientists and biotech company Moderna, has already been tested in humans and is poised for an expanded phase of testing, including 30,000 individuals, starting on 27 July. Half of the participants in the group will receive the Moderna vaccine and the other half will receive a placebo.

An initial study of the vaccine involving 45 healthy adults was published 14 July in The New England Journal of Medicine. In this study, the vaccine was found to induce a COVID-19 immune response, indicating the vaccine could hold potential for virus prevention.

If you value our service, if you have turned to us in the past few days or weeks for verified, factual updates, if you have watched our live streaming of press conferences or sent an article to a friend... please consider a donation. Quality local journalism was at risk before the coronavirus crisis. It is now deeply threatened. Even a small amount can go a long way to sustaining our mission of informing the public. We need our readers’ financial support now more than ever.