COVID-19: What We Know Now: The Latest Updates to Your COVID-19 Questions - Q&A with Gabriel Espinoza, MD. What Disinfectants Kill COVID-19? What is the Progress of a Vaccine? Are Cloth Masks Effective? Are We Experiencing A Second Wave? Are Kids at Risk?

Gabriel Espinoza, MD graduated from the UC Davis School of Medicine and has since amassed experience in caring for critically ill patients in acute care hospitals and in patients in primary care and emergency settings.  

Some of the topics he has focused on in his medical career include various areas in public health, health, and fitness. Dr. Espinoza currently works as the Family and Community Outreach Associate in San Francisco, CA. All opinions expressed here are his own.

Editor's note: This article was initially posted during the summer of 2020 and has not been updated to reflect the current scientific discoveries of COVID-19. For more up-to-date information, please refer to the Centers for Disease Control and Protection website. 

This is Part 4 of our COVID-19 series. Please see parts one, two, and three below: 

  1. Coronavirus (COVID-19) - What You Should Know
  2. Can Microwaving Mail Kill the Virus? Can You Get COVID-19 Twice? Answering Your Questions about COVID-19
  3. What's the Safest Way to Shop? Are Certain Blood Types at Higher Risk? Answering Your Questions about COVID-19


Are There Multiple Strains of COVID-19 Circulating? 

COVID-19 or Coronavirus Disease 2019 is caused by a coronavirus, specifically the novel coronavirus, SARS-CoV-2. A coronavirus is a type of virus that can cause respiratory, gastrointestinal, and central nervous system infections. According to the Centers for Disease Control (CDC), seven types of coronaviruses can infect people of all ages. In the past century, different types of coronaviruses have caused epidemics, including Middle Eastern Respiratory Syndrome (MERS-CoV), which first appeared in 2012, and Severe Acute Respiratory Syndrome (SARS), which appeared in 2002. 

Like many viruses, coronaviruses undergo mutations when dividing within a host. Some of these mutations may be minor, like changing a part of a protein. Some can be major, like changing an entire structure of the virus. A study by Tang et al.1 identified two subtypes, the L and S. However, due to changes in the amino acids of one of the proteins—since these were found in isolates from patients and were part of the same protein structure—there is still only one strain of the SARS-CoV-2 that causes COVID-19. 

Woman wearing a mask coughingWoman wearing a mask coughing

Can You Catch COVID-19 Twice? 

Research on whether full immunity occurs after recovery from COVID-19 is ongoing. The immune response to the SARS-CoV-2 virus that causes COVID-19 has a wide spectrum, ranging from little or no symptoms to severe symptoms requiring critical medical intervention due to rampant uncontrolled inflammatory response from the body. To date, there has been no confirmed reinfection after being infected by the virus that causes COVID-19. 

Case reports have shown that people who recovered from COVID-19 and had their nose and throat swabbed after 10 days without symptoms were detected to have SARS-CoV-2 but had no symptoms.2 Thus, although limited data are currently available, some immunity exists after recovery from COVID-19.  

What Are the Symptoms Associated with the Virus? 

COVID-19 can present with a variety of symptoms. Typical symptoms experienced by the majority of infected people include a fever with a temperature equal to or greater than 100.4 F or 38 C, fatigue, body aches, and cough. Other atypical symptoms reported in infected individuals include headache, nausea, vomiting, and even diarrhea. Shortness of breath is a severe and critical symptom of those infected with the virus and may require hospitalization.3

If you have been in contact with anyone who tested positive for COVID-19, it is recommended that you get tested immediately, monitor for any symptoms, and self-isolate for 14 days. If you begin to experience shortness of breath or any other concerning symptom, it’s important to contact your medical provider.  

Who Are the Most Susceptible Populations? 

Because this is a newly emerging infectious disease, the whole population is vulnerable to COVID-19. Parts of the population are at a higher risk based on age and also preexisting conditions. The majority of people with confirmed cases have been 30–69 years of age, with the majority of those requiring hospitalization being 50 years or older. Less than 1% of the patients hospitalized were under the age of 10. Individuals with high blood pressure, asthma, Chronic Obstructive Pulmonary Disease (COPD), emphysema, and diabetes have a significantly increased risk of infection. Also, any person taking medication that suppresses the immune system is more susceptible to COVID-19.  

Elderly women sitting a bedElderly women sitting a bed

How Long Is an Infected Person a Carrier or a Risk to Others? How Long Does Someone Shed the Virus While Infected? 

As COVID-19 emerged in November 2019 in the Wuhan province of China, it was imperative to define the incubation period of the virus to determine the best method to control the spread and isolate infected patients as early as possible. In a case series of 78 patients, people infected with COVID-19 who were asymptomatic had an eight-day average of viral shedding. Those who had symptoms of fever, fatigue, and coughing had a 19-day average of viral shedding, with a range of 16–24 days. 

The study showed that although those who were asymptomatic had a shorter duration of viral shedding, they may have been unaware of their infection status, not isolated themselves, and unknowingly spread it to others.4 This is why it is recommended that anyone who has been in contact with someone who tested positive for COVID-19 is tested and self-isolate for 14 days. 

Is There Progress on a COVID-19 Vaccine? 

There is an emergent need to develop and distribute a vaccine that is safe and effective enough to immunize a large population of individuals. To create this vaccine in a speedy, effective, and safe manner, the pharmaceutical industry, government agencies, and academia are collaborating to move swiftly. The type of vaccine being developed instructs the body to make antibodies against the viral proteins. Another method under trial is one that causes the viral proteins that make the virus infectious, but these require a bit more time to develop. 

In March 2020, Phase 1 of the investigational vaccine was started in collaboration with the NIH, Emory University, and the Kaiser Permanente Washington Health Research Institute. As of early June 2020, the vaccine trial has moved to Phase 2, which means it’s now being tested on more individuals, and short-term side effects and vaccine effectiveness are being researched. 

Can Coronavirus Spread Through Feces? 

SARS-CoV-2 gains entry to human cells via the Angiotensin-Converting Enzyme 2 (ACE 2) receptor. This receptor is also found in cells in the small and large intestine, leading to gastrointestinal symptoms like nausea, vomiting, and diarrhea. The first reported patient with COVID-19 in the United States reported symptoms of abdominal pain, loose stools, and was found to have a positive polymerase chain reaction (PCR) test for SARS-CoV-2 in the stool and respiratory tract. In a systematic review and meta-analysis published in the Journal of the American Medical Association, JAMA, 12% of patients with SARS-CoV-2 reported symptoms of diarrhea, nausea, and vomiting. The virus was detected in up to 41% of patients who were tested positive for COVID-19 as well.5

This indicates fecal to oral transmission occurs, and more importantly, this may explain the rapid spread of COVID-19 in healthcare settings like nursing homes. 

Person disinfecting kitchen surfaces with a spray bottlePerson disinfecting kitchen surfaces with a spray bottle

What Disinfectants Kill COVID-19? 

The EPA has an approved list of disinfectants that are approved to kill SARS-CoV-2, the virus that causes COVID-19. These products should only be used on hard surfaces. They are not to be used on humans and are not to be ingested, as they can cause serious injury. 

These approved disinfectants include products that contain isopropyl alcohol, quaternary ammonium, and sodium hypochlorite or bleach. These include, but are not limited to, products from the Clorox brand name, Lysol, and Comet bathroom cleaner. 

Do Contrails (Condensation Trails) Spread COVID-19? 

To date, no evidence suggests that condensation trails from air travel spread COVID-19. Air travel does have its risks given the amount of time spent in security lines and airport terminals at the airport and the close proximity you will be in the airplane itself. Although planes have air circulating on flights and there are air filters, social distancing is difficult to maintain, especially on crowded flights. 

It is important to wear a mask when traveling by air, avoid touching your eyes, nose or mouth, wash your hands, and if soap and water are inaccessible, carry an alcohol-based hand sanitizer with at least 60% alcohol. 

Can Coronavirus Spread Through Food or Water? Does Cooking Kill the Coronavirus? 

SARS-CoV-2 and other coronaviruses spread mainly through person-to-person contact through respiratory droplets when someone sneezes, coughs, or talks. If someone who is infected with the virus has touched their nose or mouth and then touches a surface, which can include food or the packaging, it may be possible to spread the virus. 

However, according to the CDC, this is not the main way the virus spreads and no evidence indicates that handling food or consuming food is associated with COVID-19. It is recommended though that you wash your hands with soap and water for at least 20 seconds before eating. If soap and water are not available, you should use an alcohol-based hand sanitizer, as it’s important to follow good food safety practices to reduce the risk of contracting a disease from other common foodborne viruses or bacteria. 

Person washing their handsPerson washing their hands

Does Drinking Alcohol Kill the Coronavirus? 

Drinking alcohol does not kill the coronavirus. Once the virus is in your body, it’s in the cells of the body. In fact, drinking alcohol, especially in heavy amounts, will weaken the immune system. Alcohol also alters your thoughts, judgment, decision-making, and behavior. 

It’s recommended that you avoid large amounts of alcohol and stay sober so that you can remain vigilant and make clear decisions about yourself and others in your family and community. If you are taking any medications, avoid mixing your medications with alcohol. 

Do Any Antivirals Work Against COVID-19? 

There is currently no specific antiviral treatment for COVID-19, but some antivirals developed for other viruses have shown to be effective against SARS-CoV-2. One of these is Remdesivir, which was approved by the FDA in May for the use in severe cases of COVID-19. Remdesivir is an antiviral that was initially created to treat Ebola, which is not a coronavirus. It targets a protein that is essential for the virus to make more copies of itself. Since the virus is unable to make more copies, it will not spread and infect other cells. 

In a study published in the New England Journal of Medicine, NEJM, investigators compared Remdesivir to placebo in 1,000 patients and showed an improvement in clinical condition from an average of 15 days to 11 days with Remdesivir. Developing antivirals is a difficult process, as the medication has to target the replicating virus without killing the human cells. 

Other medications that initially seemed to have some benefits against COVID-19 were antimalarial medications like chloroquine and hydroxychloroquine. These compounds in vitro demonstrated that they prevented the entry of SARS-CoV-2 into cells. But in clinical trials, these compounds showed more harm than good. The biggest risk of hydroxychloroquine is cardiac arrhythmias and other cardiac complications. Due to these adverse effects, hydroxychloroquine is no longer recommended as a treatment for COVID-19.6 

Which COVID-19 Antibody Test Is the Best? How Accurate Are the Different Antibody/PCR Tests? What Is the Likelihood of False Positives? 

Since the emergence of COVID-19, there has been a rush to develop testing to help diagnose virus infection or if an immunity to the virus has been obtained. The Foundation of Innovative New Diagnostics (FIND) and the World Health Organization (WHO) are undertaking the evaluation of the many serological antibody tests—tests that look for antibodies in blood—that have been developed. 

Antibody tests are used to determine if a person has been exposed to SARS-CoV-2; they do not detect if you are currently infected with COVID-19. A study in France showed that it takes on average eight days from the start of symptoms to develop antibodies to SARS-CoV-2. Due to this lag time, researchers noted that the sensitivity of antibody tests increases from the onset of symptoms, with rates ranging from 40–60% at 8 days of symptoms to greater than 95% after 15 days of symptoms.7 

In another study, German researchers found varying sensitivity rates of antibody tests, ranging from 53% to 94%. These rates are dependent on the type of population being tested, and how high the pretest probability is, which means how likely was it that the population exposed to COVID-19.8  

PCR tests determine if someone is currently infected; these are the tests that take samples from deep in your nose and back of the throat. Evidence has shown that these tests have excellent specificity and sensitivity, but remember that no test can always be 100% accurate, and false negatives have been reported. According to a JAMA review, the sensitivity of the PCR test is 33% four days after exposure to SARS-CoV-2, with it increasing to 62% at symptom onset, and at 80% three days after onset.6

What Is the Likelihood of Catching the Virus Outdoors Compared to Indoors? 

In general, indoor spaces with less ventilation, where it’s harder to keep people apart, increase the risk of contracting COVID-19. This virus spreads through respiratory droplets, and if people are within close proximity to each other in a place with poor air circulation, they are increasing their risk of exposure drastically. Respiratory droplets are released anytime you talk, yell, laugh, sing, whistle, sneeze, and cough. 

Going outside lowers the risk, but there is still a risk of contracting the virus. If you decide to venture outdoors, wear a face mask, especially if you will be interacting with people that you do not live with. What is even more critical than the face mask is to practice social distancing, and try to avoid activities that will require you to be less than 6 feet apart. Ensure that you wash your hands with soap and water, and if you don’t have access to this, then use an alcohol-based hand sanitizer. 

Is It True That Someone May Test Positive for COVID-19 If They Had a Vaccine Such as the Flu Vaccine or Other Vaccines? 

The virus that causes the flu is a different virus from the one that causes COVID-19. Because of this, if you’ve had the flu vaccine, you will only be protected against the influenza virus. 

Additionally, when you get tested for the flu and COVID-19, the PCR test is only looking for the genetic material of the virus being tested. Because the influenza virus and the SARS-CoV-2 that causes COVID-19 are completely different viruses, they have different genetic material and will require a specific test for each. 

The influenza vaccine is made from inactivated, not infectious, influenza virus proteins that help produce an immune response against only the influenza virus. The body’s immune system has been designed to be specific; it detects the germ that causes a specific disease. This is why a vaccine for the measles virus only works for the measles virus, and will not cross-react with other viruses like SARS-CoV-2. 

Remember, that by getting tested for COVID-19, you are only getting tested for the virus that causes COVID-19, SARS-CoV-2. 

What Is the Likelihood of Catching Coronavirus from Secondhand Exposure, Such as Someone in My Daughter’s Daycare Had COVID-19, and I Catch It from My Daughter Since She Is Probably Asymptomatic? 

COVID-19 spreads through close contact with people. Because some who may be asymptomatic, without symptoms, may also be able to spread the virus, it is important to practice good hand hygiene and wear face masks. It is also important to know if anyone at any public space has come in contact with someone who has tested positive for COVID-19. 

Many businesses have set up screening questions asking for this information, which helps identify who may be at risk of spreading or contracting COVID-19. If your child is attending a child care program, ensure that the program has implemented social distancing strategies, intensified its cleaning and disinfection efforts, screens for symptoms for child and family at arrivals, and modifies their drop-off and pick-up procedures. When your child gets home, ensure they wash their hands with soap and water for at least 20 seconds.  

Picture of a maskPicture of a mask

What Makes Coronavirus So Contagious? 

The novel SARS-CoV-2 is so contagious because it is a virus that spreads through droplets, and we don’t have a defense mechanism against it. Because it’s new, our bodies have not been exposed to this type of virus before, and thus the virus can enter human cells more easily. Once the virus has gained entry, the virus hijacks the cell’s machinery to replicate itself. 

When millions of virus particles are released from infected cells, they infect more cells before the immune system can start to respond. As the virus makes more copies, people who are infected may not even start to show symptoms like fever, cough, or fatigue and may unknowingly spread the virus. Thus, the combination of novelty and incubation period before showing symptoms makes the virus particularly contagious. 

Are Cloth Masks Effective? 

The main purpose of face masks is to function as a barrier to prevent droplets that can travel when we talk, raise our voice, sneeze, or cough. This is known as source control, indicating the prevention of the spread of something directly at the source. Since COVID-19 spreads when people are in close contact (fewer than 6 feet apart) and through respiratory droplets, the use of face coverings dramatically reduces this risk of exposing others if you are contagious. 

According to the CDC, all people 2 years of age or older should wear a cloth face mask in public and when around people with whom you do not live. Avoid masks with exhalation valves. Although they make it easier to breathe, the valve releases unfiltered air and will not protect others if you are contagious.  

Although the filtration capability of cloth masks is usually much lower than that of medical masks and respirators, multilayer, high thread count cloth masks that fit around the face appropriately and are made of water-resistant fabric, may provide reasonable protection against SARS-CoV-2. While cloth masks are not guaranteed to protect you or others from contracting COVID-19, they may help reduce the risk of exposure to others.

Other types of masks are used for medical personnel: surgical and the N95 respirator masks. Surgical masks are engineered with special paper, designed to protect others from the wearer and to block large particles. N95 respirators are designed to form a tight seal around the nose and mouth of the wearer. They require specific fitting by qualified personnel and are a great way to protect the wearer and the people around them.  

Was COVID-19 Made in a Lab? 

According to a study in the Journal of Nature Medicine, investigators concluded that it was improbable that SARS-CoV-2 was created from genetic manipulation from SARS-CoV. The investigators proposed two scenarios that may explain the origin of the virus.

The first is that it evolved in a different animal source, and bats became the reservoirs to this virus, and accidentally developed the receptor proteins that made it infectious in humans. The second scenario is that a progenitor to SARS-CoV-2 jumped into humans, and through evolution and adaptation, it acquired the receptor proteins necessary to infect humans. 

Be mindful of the misinformation on social media and the many theories on the origins of COVID-19. Some believe that the spike protein that makes SARS-CoV-2 infectious is derived from a similar protein structure in HIV called glycoprotein 120. This is due to the presence of Dr. Anthony Fauci’s name on the patents for immune therapy against this protein. 

It’s important to note that these ideas may present a health risk, due to the possible correlation between the belief in these theories and laxity in health-protective behavior, like avoiding social distancing or wearing a mask in public.10 

Child in bed with a care giver taking their temperatureChild in bed with a care giver taking their temperature

Are Kids at Risk for COVID-19? 

Although children have fallen ill with COVID-19 and severe cases of the illness have been reported, children do not appear to be at a higher risk for COVID-19 compared to adults. In children, symptoms of COVID-19 can include fever, cough, and difficulty taking deep breaths. 

Based on the data for children who have been infected by COVID-19, some cases have developed into Multisystem Inflammatory Syndrome. The main reason why this condition develops in children after being infected with COVID-19 is still under investigation. 

It’s important to seek medical attention if your child has trouble breathing, pain, or pressure in the chest, confusion, inability to wake or stay awake, blueish or purple lips, and severe abdominal pain. 

Will There Be a Second Wave in the Fall? Are We Experiencing a Second Wave Now? 

As of July, there are more than 2.8 million cases of COVID-19 in the United States, with an average of 50,000 daily cases, and the death toll is now greater than 100,000. The current hot spots of cases are in the Southern and Southwest United States. This is higher than the initial height on April 6, 2020, which was 43,438 cases per day. 

We are likely still in the first wave of the virus given the laxity of shelter-in-place policies by some states. Without a central health enforcement agency in the United States, the CDC establishes guidelines only, and each state and their respective health departments implemented their own policies while trying to follow CDC guidelines. 

Due to the diversity in policies, different dates of reopening economies, lifting sheltering in place laws, and laxity in enforcement of face masks, the effects of these decisions are seen as a continued first wave that affects millions. 

Given that cases of respiratory illnesses rise during the fall and winter seasons, we may also be faced with a higher rate of infection during the upcoming fall and winter months if we continue with lax laws. We must take the lessons that we are learning now and not forget we are in a pandemic, and that vigilance is key as we actively work on developing an effective and safe vaccine. 

This is Part 4 of our COVID-19 series. Please see parts one, two, and three below: 

  1. Coronavirus (COVID-19) - What You Should Know
  2. Can Microwaving Mail Kill the Virus? Can You Get COVID-19 Twice? Answering Your Questions about COVID-19
  3. What's the Safest Way to Shop? Are Certain Blood Types at Higher Risk? Answering Your Questions about COVID-19


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  2. Kirkcaldy RD, King BA, Brooks JT. COVID-19 andPostinfectionImmunity: Limited Evidence, Many Remaining Questions. JAMA. 2020;323(22):2245–2246. 
  3. Guo, G., Ye, L., Pan, K., Chen, Y., Xing, D., Yan, K., Chen, Z., Ding, N., Li, W., Huang, H., Zhang, L., Li, X., &Xue, X. (2020). New Insights of Emerging SARS-CoV-2: Epidemiology, Etiology, Clinical Features, Clinical Treatment, and Prevention. Frontiers in cell and developmental biology, 8, 410.
  4. Yang R,GuiX, Xiong Y. Comparison of Clinical Characteristics of Patients with Asymptomatic vs Symptomatic Coronavirus Disease 2019 in Wuhan, China. JAMA Netw Open. 2020;3(5):e2010182. 
  5. ParasaS, Desai M, Thoguluva Chandrasekar V, et al. Prevalence of Gastrointestinal Symptoms and Fecal Viral Shedding in Patients With Coronavirus Disease 2019: A Systematic Review and Meta-analysis. JAMA Netw Open. 2020;3(6) 
  6. WiersingaWJ, Rhodes A, Cheng AC, Peacock SJ, Prescott HC. Pathophysiology, Transmission, Diagnosis, and Treatment of Coronavirus Disease 2019 (COVID-19): A Review. JAMA. Published online July 10, 2020. 
  7. Demey, Baptiste et al. “Dynamic profile for the detection of anti-SARS-CoV-2 antibodies using four immunochromatographic assays.” The Journal of infection, S0163-4453(20)30244-9. 7 May. 2020.
  8.  Horvath, K.,Semlitsch, T.,Jeitler, K., Krause, R., & Siebenhofer, A. (2020). Antibody tests for COVID-19: What the results tell us. Journal of Evidence, Education and Quality in Health Care, S1865-9217 (20) 30049-0. 
  9. Andersen, K.G.,Rambaut, A., Lipkin, W.I., et al. The proximal origin of SARS-CoV-2. Nat Med 26, 450–452 (2020).
  10. Allington, D., Duffy, B.,Wessely, S.,Dhavan, N., & Rubin, J. (2020). Health-protective behaviour, social media usage and conspiracy belief during the COVID-19 public health emergency. Psychological medicine, 1–7. Advance online publication.