COVID-19 Questions Scientists Are Still Looking to Answer

COVID-19 Questions Scientists Are Still Looking to Answer

    

    Since COVID-19 first appeared 6 months ago in Wuhan, China, the virus has spread around the world, turning into a pandemic that has killed over 500,000 people. As a result, scientists and doctors have been working tirelessly to better understand COVID-19 and how it works. As more insights are being discovered about COVID-19, more questions arise. An article published in Nature on July 3, 2020, highlights the top 5 pressing questions that researchers are still finding answers for.

Why do people respond so differently?

    While some people infected with COVID-19 show little to no symptoms, others may experience symptoms as severe as fatal pneumonia. There's a wide range of how people respond to COVID-19 and researchers are looking for human gene variants that may explain some of these differences. A small study discovered that one possible explanation lies in a region of the genome that determines ABO blood type. (See Blood type and COVID-19) People who carry this particular gene variant are more likely to develop severe respiratory failure. However, this gene variant seems to play a small role in disease outcome, so other scientists are looking for mutations that may play a more significant role. Research shows that susceptibility to other infections have been pinned down to mutations in a single gene. Researchers suspect that this will also be true for COVID-19.

COVID-19 Immunity and how long it lasts

    Most COVID-19 immunity work is focused on "neutralizing antibodies" which bind to viral proteins and prevent infection. Studies have found that levels of "neutralizing antibodies" or immunity remains high a few weeks after infection but then begins to lower. However, it's been found that people with more severe cases of COVID-19 will have high levels of antibodies/immunity for a longer period of time after their initial infection. Researchers are still unsure what levels of neutralizing antibodies are needed to withhold COVID-19 reinfection or reduce symptoms in a second infection. According to Nature Magazine, Andres Finzi, a virologist at the University of Montreal, "plans to study the role of antibodies that bind to infected cells and mark them for execution by immune cells." However, antibodies aren't the only molecules that contribute to immunity. T-cells have also shown to be significant in long-term immunity. The immune system is much more complex than just antibodies alone. Because of this, there isn't a clear or measurable marker in the body that can determine how long immunity lasts.

Virus Mutations

    Every virus, including COVID-19, is known to mutate as it infects people. Scientists are looking for mutations that could change the virus' properties such as transmission or infection severity. It's important to know if a virus has become more severe because mutations like these could lessen the effectiveness of vaccines. However, most mutations have little impact and it's challenging for scientists to pick out significant mutations. There is still lots of research to be done to better understand how the coronavirus has mutated since its first outbreak and how the mutation translates to human infections.

How well will vaccines work?

    Right now, an effective vaccine is the only way we can escape the ongoing pandemic. About 200 companies around the world are in the process of developing a vaccine against COVID-19. (See Vaccines and Clinical trials). Studies from animals show that vaccines do a good job in preventing lung infection/pneumonia but not at blocking infection in other parts of the body. The results indicate that the COVID-19 vaccine could prevent severe diseases but not the spread of the virus. Human data also suggests that COVID-19 vaccines prompt our body to make strong neutralizing antibodies which can block infection. However, it's unclear whether the levels of these antibodies are high enough to prevent infections or how long they last. With scientists around the globe working to develop a vaccine and lots of government funding, the COVID-19 vaccine will be available in a record breaking time. However, scientists believe it may not be completely effective.

Where does the virus originate from?

    Many researchers believe that COVID-19 originated in horseshoe bats. Two types of coronaviruses, closely related to SARS-CoV-2, have been found in these bats. One type, RATG13, was found in intermediate horseshoe bats in Yunan, China in 2013. The RATG13 genome was a 96% match to SARS-CoV-2.  RmYN02, the second type of coronavirus, was found in Malayan horseshoe bats. The RmYN02 genome was a 93% match to SARS-CoV-2. Scientists believe the horseshoe bats in Yunan are the most probable origin of SARS-CoV-2, with the 4% difference in genomes being a result of evolution. It's believed that the coronavirus passed through an intermediate host before reaching humans. Researchers suspect that SARS first traveled from horseshoe bats to civets before reaching humans. The only sure way for scientists to trace the journey of the virus is finding an animal host with a genome that matches more than 99% of SARS-CoV-2. However, this is a complicated prospect as humans have begun to spread the virus to other animals including dogs, cats and mink. So far, studies to isolate the virus from wildlife, including civets, have not produced any results.

Sources

1. Callaway, Ewen, et al. “Six Months of Coronavirus: the Mysteries Scientists Are Still Racing to Solve.” Nature News, Nature Publishing Group, 3 July 2020, www.nature.com/articles/d41586-020-01989-z.