1. Ada
  2. Editorial
  3. Medicine & health
  4. What you should know about COVID-19

What you should know about COVID-19

This article will be updated regularly based on the most recent medical knowledge.

Since the start of 2020, a new respiratory infection outbreak called COVID-19 has spread through Asia to the rest of the world. This new type of coronavirus is called SARS-CoV-2.

At the beginning, the majority of COVID-19 cases were reported in China, but the outbreak is now affecting the whole world. More than 200 countries have reported COVID-19 infections, with many experiencing widespread transmission. The outbreak has been declared a pandemic by the World Health Organization (WHO) and countries have implemented unprecedented measures to fight the spread of COVID-19. Do you need to be worried? What should you know about this outbreak and the new virus? Our medical professionals answer some of your most frequently asked questions.

Risk

How likely am I to catch COVID-19?

COVID-19 has reached almost every country in the world. But if you aren’t in an area where COVID-19 is spreading locally, your chances of getting it are currently still relatively low. If you are in an area with local transmission, you should take the risk seriously and follow the recommended prevention measures. In either case, the situation is changing rapidly, and it’s good to keep up to date on the current situation from your local health authority.

Why do some people get more serious symptoms than others?

While people of all ages are susceptible to COVID-19 infection, four out of five have a mild to moderate illness and recover. Those over 60 years old and with pre-existing medical conditions, such as cardiovascular disease, diabetes, or high blood pressure, are more vulnerable to becoming seriously ill. Children seem to be less affected.

What are the typical COVID-19 symptoms?

Typical symptoms are fever, dry cough, shortness of breath, and fatigue. But COVID-19 patients also showed less typical symptoms like headache, generalized muscle aches and pains, sore throat, diarrhea, reduced or lost sense of smell and taste, runny nose, and red or sore eyes.

Is it possible to be infected without having symptoms?

Evidence is emerging that many people with COVID-19 don’t develop symptoms. A recent study in an affected village in Italy showed that 43.2 percent of confirmed cases didn’t develop any COVID-19 symptoms. Asymptomatic COVID-19 infections may be common in pregnant women, with one study finding only one in ten developed symptoms following infection. Children are also often asymptomatic.

What should I do if I think I’m infected?

As the measures differ between countries, it’s important to check with your local public health authority to get advice on what to do. Before going to a doctor’s office or the emergency room, call ahead and tell them about your contacts, and symptoms, and then follow their advice. In the meantime, avoid contact with others and don’t travel. Cover your mouth and nose with a tissue or your sleeve (not your hands) when coughing or sneezing, and wash your hands often with soap and water for at least 20 seconds. Use an alcohol-based hand sanitizer if soap and water are not available.

If you are worried you may be infected, you can now use the Ada COVID-19 assessment and screener Please keep in mind that further testing will be necessary to diagnose COVID-19.

Does COVID-19 cause death?

It is possible to die from COVID-19 complications. A small percentage (currently around 3.4 percent) of people who are infected become so ill that they die – which means the vast majority of infected people recover. Mortality is much higher in those over 60 and with pre-existing medical conditions.

Why are the death rates so different among countries?

If you follow the media reports, it becomes clear that the COVID-19 death rate, also known as the case fatality rate (CFR), differs a lot from country to country. In Italy and Spain, it’s around 10 percent, and in Germany or Norway, it’s 1 to 2 percent.

There are several possible explanations. A recent study calculated the real number of cases by country, taking underreporting and testing capacity into account. It concludes that until the end of March, 15 percent of the Spanish population was already infected, compared to only 0.8 percent in Germany. So, the stages of the pandemic in each country seem to differ a lot. CFR might change in countries over time.

Additionally, the number of intensive care unit (ICU) beds varies a lot. Countries with lower CFR had up to three times more ICU beds per population than countries with higher CFR. Also, different testing strategies between countries impact CFR.

Is influenza a coronavirus?

No, influenza viruses are different from coronaviruses – even though they cause similar symptoms and also mainly spread through respiratory droplets.

An illustrative representation of the SARS-CoV-2 coronavirus.

Transmission

How is COVID-19 transmitted?

COVID-19 transmission is similar to other respiratory viruses. It mainly spreads through small droplets that form when an infected person sneezes or coughs. Usually, these droplets only reach people (or surfaces) close to the infected person. The general rule is that droplets can spread one to two meters but not further than that. The virus does not seem to be airborne or passed through the fecal-oral route.

Is the virus only spread by sick people?

People who are not or not yet symptomatic may also spread COVID-19. Studies suggest asymptomatic transmission could be responsible for 40–60 percent of infections, and it seems that people are most infectious the day before symptom onset.

How long does the virus survive on surfaces?

Early findings indicate that COVID-19 can remain on surfaces from a few hours up to several days, depending on the type of surface, temperature, and humidity. You can use a standard disinfectant to clean surfaces to prevent infection. COVID-19 doesn’t spread through letters or packages coming from an affected region.

What is the incubation period for COVID-19?

The incubation period is the time between the infection and the first onset of symptoms. The average incubation period for COVID-19 is around five to six days but can range from one to 14 days.

Can humans get COVID-19 from animals?

The origin of the virus is still unclear, but research points towards bats as the source. Until now, there are very few reports of COVID-19 in household pets (one cat and one dog) and no documentation of transmission from them to humans. Also, a tiger in a New York zoo tested positive for COVID-19, likely becoming infected through proximity with a sick zoo employee.

How long does a person with COVID-19 remain infectious for?

There is still little available information about the duration of infectiousness. The virus can be detected for up to several weeks in samples from infected people. But that doesn’t mean the virus is active and infectious. One small study showed that the active virus was detectable in throat swabs for up to four days after symptom onset, and up to eight days in sputum samples. The active virus wasn’t detected in blood, stool, or urine. The results of this study suggested that people remain infectious for up to eight days, with reduced infectiousness after four days. These results need to be confirmed in a more extensive study.

Can I get COVID-19 more than once?

Again, we still know little about COVID-19, especially regarding the longer-lasting questions. But people can develop immunity that lasts for some time after infection with other coronaviruses. Scientists have also carried out a small study in monkeys who have had COVID-19. These monkeys were not able to catch the disease again, so immunity can be assumed. These are very early results of a small study, so further tests are needed, but the preliminary results might give some indication of possible immunity in humans.

Prevention

How can I prevent a COVID-19 infection?

Avoiding exposure to the virus is the best way to prevent infection. Standard measures to prevent the spread of respiratory viruses apply:

  • Wash your hands frequently with soap and water for at least 20 seconds. If soap and water are not available, use an alcohol-based hand sanitizer.
  • Avoid touching your eyes, nose, and mouth with unwashed hands.
  • Remain at least two meters away from anyone who has a fever and cough.
  • Stay home if you have symptoms, even mild ones.
  • Cover your cough or sneeze with a tissue and then throw the tissue in the bin.
  • Clean and disinfect frequently touched objects and surfaces.

Should I wear a mask?

Surgical or simple cloth masks are more effective at preventing infected people from spreading diseases than protecting those who aren’t sick. You can wear a mask if you have respiratory symptoms – like coughing or difficulty breathing – to limit the spread of respiratory droplets, but you don’t need a mask if you don’t have respiratory symptoms. However, some countries have recently made it mandatory to wear masks in public to decrease the spread of virus by those who might be infected. It is yet to be proven if this will be effective.

Medical professionals use special filter masks that are fitted to their faces and can reduce the risk of transmission. The public shouldn’t use these masks, as they are in short supply and are required to keep medical professionals safe while they care for others.

Treatment

Is there a vaccine or drug for COVID-19?

There is currently no available vaccine. Vaccine production is a complicated and time-consuming process that usually takes years. In certain circumstances, like with new influenza viruses, there are established methods that can accelerate this process. That said, COVID-19 was first detected at the beginning of January 2020: Many studies are ongoing, but even in the ideal scenario, it will take several months before a vaccine is available and can be tested and used widely.

There are also many ongoing studies to test pre-existing drugs that were developed to fight other diseases such as malaria, ebola, or HIV. Tests should show if they are effective in treating COVID-19 patients. The initial results should be available soon.

COVID-19 or the common cold – how can I tell the difference?

Symptoms of the common cold and COVID-19 are very similar. That’s why understanding the significance of exposure to the virus is so important to differentiate between the two. Along with showing the typical symptoms of fever, dry cough, shortness of breath, or fatigue, people with COVID-19 have also typically been in an area where the virus is already spreading locally, or in contact with a person who has the virus.

The similarity between a cold and COVID-19 in many cases means that, for some people, the infection can seem no worse than a common cold.

How is COVID-19 diagnosed?

Infection is confirmed by testing respiratory samples in specialized laboratories. The first antibody blood tests to identify infection and immunity are under evaluation.

Perspective

When will the outbreak be over?

It’s hard to say when the outbreak will be over. At the moment, there’s very little indication that it will stop soon. As with the mild influenza pandemic of 2009/2010, COVID-19 will probably continue spreading worldwide. Even though it’s possible that it could slow down by spring – much like seasonal influenza each year – early analysis of the virus indicates that increasing temperatures will not reduce transmission significantly.

What is ‘social distancing,’ and how does it ‘flatten the curve’?

Put simply, ‘social distancing’ means staying at home when you can. When you do leave the house, keeping two meters away from people you don’t live with can help reduce infection.

Some countries have introduced strict social distancing measures. They have closed schools, offices, bars, cafes, and shops, or only allow people to leave their house when it’s absolutely necessary.

This is helping to ‘flatten the curve,’ postponing and reducing the peak of the pandemic, resulting in fewer simultaneous cases, and ideally, fewer cases overall. During the pandemic, this limits the burden of the outbreak on health systems and helps free up ICUs for the most serious cases.

Slower acceleration in number of cases = Reduced peak in number of cases and demand on healthcare infrastructure

Are the measures working?

To judge if the control measures are working we have to look at how we can assess their success. One important indicator is the reproduction number (R0) of an infectious disease. This number describes how many people are infected on average by one person. The R0 can be up to 18 for measles, which is the most contagious known disease. Seasonal influenza tipically has an R0 of one to two. The reproduction number is affected by immunity in the population (including available vaccinations), transmission routes, and control measures. Without control measures, the COVID-19 R0 was estimated to be three to four. This resulted in the exponential growth of infections in the beginning.

Epidemiologists use R₀, which stands for reproduction number, to indicate the average number of people that one person will infect. Here are the R₀ values for five viruses: Seasonal influenza 1-2, Ebola 1.5-2.5, COVID-19 3-5, Chickenpox 10-12, Measles 12-18

With the control measures of social distancing, the estimated COVID-19 R0 in many countries is around one now. This shows that the measures were effective and that we have flattened the curve. But we need to keep it up until we have reached a higher immunity, naturally or through vaccines, to avoid an increase in the number of infections again.


Writer:

Dr. Andreas Gilsdorf

Andreas is Ada's Director of Epidemiology and Public Health.