Your questions about risk factors for getting coronavirus

What's your risk of Covid-19?

Are you wondering what your risk is when planning events or outings?

This site provides interactive context to assess the risk that one or more individuals infected with COVID-19 are present in an event of various sizes. The model is simple, intentionally so, and provided some context for the rationale to halt large gatherings in early-mid March and newly relevant context for considering when and how to re-open. Precisely because of under-testing and the risk of exposure and infection, these risk calculations provide furher support for the ongoing need for social distancing and protective measures. Such precautions are still needed even in small events, given the large number of circulating cases.

This map shows the risk level of attending an event, given the event size and location (assuming 10:1 ascertainment bias). Click the image to go to the page and find your event risk level.

COVID-19 Event Risk Assessment Planning Tool
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Patients with coronavirus have a number of coagulation (blot clots) abnormalities which can result in excessive tendency towards creating clots (thrombosis) and it is clear from the evidence that this may be a big risk factor for death in severely ill patients and needs to be carefully treated and studied further. The mechanisms are not currently well understood but involve:

  • Endothelial injury
  • Stasis
  • Hypercoagulability.

Clinical feature can include, often despite prophylactic-dose anticoagulation:

  • Venous thromboembolism including extensive deep vein thrombosis
  • Pulmonary embolism which is seen in up to one-third of patients in the ICU even when  anticoagulation is given.

Autopsy studies also demonstrate that hypercoagulability is common in the most severely ill patients. In one study where a post-mortem was performed on 21 patients that died from coronavirus, a pulmonary embolism was found in four and in those who had the data available  and it was found that almost 50% of the deceased had mircrothombi in alveolar capillaries.

In another study of 12 post-mortem examinations 7 of 12 had bilateral deep vein thrombosis (clots) in the legs with all cases having been both bilateral and interestingly unsuspected in all patients. Of those 12 - the cause of death in at least 4 was determined to be a pulmonary embolism - clots in the lungs.

Studies also demonstrate that widespread clothing and micro clots were significantly more prominent in the lungs of the patients who died of coronavirus compared with the lungs of controls who died of for example the flu.

Risk factors for hypercoagulability

Studies indicate - due to the fact that most patients have risks such as obese males, other medical conditions with heart disease, high blood pressure and diabetes being common.

Other clinical presentations

The data regarding how the tendency for thrombosis can present includes:

  • Arterial events such as an increased incidence of strokes,
  • acute limb ischemia,
  • potentially heart attacks and
  • microvascular clotting and even bleeding.

Is Pregnancy a Risk Factor for Coronavirus?

A very important question in regards to pregnancy is whether pregnancy is a risk factor for COVID-19, in terms of being infection, severity of the disease and the death rate in mother and fetus.

The answers seems to be that yes it is a risk factor for at least severity of the disease in the mother and there is insufficient data regarding the fetus outcomes currently. A recent study from Sweden has found a five times greater risk of ICU admission and four times the risk of receiving mechanical ventilation than non pregnant women.

Now the CDC has released the results of its study lasting from January 22–June 7, as part of COVID-19 surveillance. Of the 91,412 women with laboratory-confirmed COVID-19 infections; nine percent were pregnant.

Among pregnant women with coronavirus, almost a third - 31.5% - reported having been hospitalised compared to almost a fifth of that amount  - 5.8% - in women who were not pregnant.  After adjustments for a variety of known risk factors such as age and other medical conditions, - the relative risk of being hospitalised for a pregnant woman was 1.5 times that of a non-pregnant woman and 1.7 times the risk for intubation and mechanical ventilation. Interestingly however the rate of death was similar suggesting that though the disease is more severe - it does not cause a higher mortality rate -

The CDC wrote that "To reduce occurrence of severe illness from COVID-19, pregnant women should be counseled about the potential risk for severe illness from COVID-19, and measures to prevent infection with COVID-19 should be emphasised for pregnant women and their families”. “We think it’s important to get the information out there that pregnant women need to take precautions,” Dana Meaney-Delman, CDC’s Covid-19 deputy incident manager, said.

The results also indicated that although data on race/ethnicity were missing for 20% of the pregnant women in the study, as with the general population, Black and Hispanic pregnant women were disproportionately impacted.

One issue with the study data needed to distinguish whether the hospitalisation was due to pregnancy related conditions or COVID-19 were not available. Also one can understand that hospitals may have a lower threshold for admitting pregnant women. However ICU admission and receipt of mechanical ventilation are distinct proxies for illness severity and the risks for both outcomes were significantly higher among pregnant women than among non-pregnant women.

The CDC further stated: "Although additional data are needed to further understand these observed elevated risks, pregnant women should be made aware of their potential risk for severe illness from COVID-19. Pregnant women and their families should take measures to ensure their health and prevent the spread of SARS-CoV-2 infection.”

Specific actions pregnant women can take include:

  • not skipping prenatal care appointments,
  • limiting interactions with other people as much as possible,
  • taking precautions to prevent getting COVID-19 when interacting with others,
  • having at least a 30-day supply of medicines,
  • and talking to their health care provider about how to stay healthy during the COVID-19 pandemic.

While the agency wasn’t able to assess the effects of the virus on the fetuses or babies born to those women since the pandemic hasn’t gone on long enough, pregnant  women who get Covid 19 might have an increased risk of preterm labor and birth, when the baby is born before 37 weeks of pregnancy. This seems to be more of a risk in people who get very sick and have pneumonia. Preterm birth can be dangerous, because babies who are born too early can have serious health problems. So it is important to talk to your doctor, nurse or midwife about any symptoms or health concerns you have, even if they don’t appear to be related to Covid 19.

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The Flu Shot and Coronavirus

Should I get the flu shot this year? Will it help against coronavirus?

It is well documented now that there is a surge of COVID-19 across dozens of states while at the same time the incidence is decreasing in others.

However as we approach flu season when it is normally recommended to get the flu shot - it is highly likely than individuals who succumb to both viruses will suffer more severe illness and a higher number of deaths - particularly in those most susceptible to either.

Due to seasonality, a return to school and indoor activities the spread of flu will occur as it does every year this fall. We know that the flu vaccine works better some years than others and we know that it decreases sickness, hospitalisations severity and death. This year however the risks are higher as folks infected by both COVID-19 and the flu are highly likely to experience greater negative impacts.

While we know that in a typical year less than 50% of adults receive the flu vaccine vs a recommended 70% as set by the Department of Health and Human Services for 2020. Additionally we know that annually typically hundreds of thousands are hospitalised and tens of thousands die - the two together however could bring significantly more disastrous results. Given that flu shots are lower historically in black and Hispanic populations in the US - and that they have had a higher rate of coronavirus infection, sickness and death than the rest of the population - this can further exacerbate the demographic differences we will see.

In addition to masks, handwashing and social distancing reducing the spread of coronavirus fortunately these same factors reduce the spread of flu infections also. This can be further enhanced by a broader vaccination of the US population particularly susceptible sub-groups such as minorities and the elderly as well as health care workers who have a much higher chance of exposure to both viruses.

Does the flu vaccine work?

Yes. It works but not 100%. That is to say that the flu vaccine is imperfect and does not cover all strains of flu (which vary annually) it has a massive impact on reducing not only the severity of flu infections but also hospitalizations and death. Furthermore side-effects are generally mild with a fleeting headache and soreness around the injection site being relatively minor and infrequent side effects. Also as the vaccine is not a live virus - it cannot cause influenza itself though people may feel some mild flu symptoms due to the body’s response to the shot.

It is strongly recommended that vaccines should be especially considered in high risk environments such as classrooms and at work for those working in dense, high-contact environments in addition to those who normally are at high risk of sickness and death from the flu.

Who pays for the flu shot?

Federal law requires health insurers to pick up the cost of annual flu vaccination, as Medicare does. Medicaid vaccine coverage varies by state. Given the massive numbers of unemployed who have lost insurance - it is therefore more important than ever this year that states and the federal government to work together to make shots free or at least very inexpensive for the uninsured.

No association between asthma and increased risk of hospitalization in patients with COVID-19

Patients with asthma were not more likely to be hospitalized due to COVID-19 compared with patients without asthma, According to new data published in The Journal of Allergy and Clinical Immunology patients with asthma are not more likely to be hospitalized than patients without asthma. .This outcome is unexpected as asthmatic patients tend have worse outcomes in viral illness which often exacerbates the asthma.

Researchers in conducting a retrospective study across 10 U.S. hospitals in examining the prevalence of asthma and comorbidities in patients with COVID-19 found that there was no significant difference in risk for hospitalization between patients with asthma and those without, after adjusting for other risk factors such as age. Furthermore the risk of hospitalization was also not higher for patients with asthma when their risk factors such as smoking, heart disease, diabetes etc were taken into account.

Importantly, the researchers reported no difference in mortality for patients with coronavirus and with and without asthma.

More studies must be done to look at the underlying immune modulation caused by asthma or asthma treatment to see what impact it may have on COVID-19 outcomes, said Anju T. Peters, MD, MSCI, FAAAI, director of clinical research in the division of allergy/immunology and otolaryngology at Northwestern University Feinberg School of Medicine one of authors of the study.

Does Blood type Affect My Risk of Covid-19

Patients with COVID-19 infection have a dramatic variability in presentation, from being asymptomatic to presenting with rapidly declining respiratory discomfort and even sudden death.

While it is understood that older aged individuals and those with greater medical issues have a higher risk according to the U.S. Centers for Disease Control and Prevention. - there are unfortunately also too many cases of otherwise healthy younger adults with severe disease who also can suffer death. As such it is important to understand what other risk factors affect outcomes.

According to a European study from the genetic analysis of 1,900 patients with severe cases of coronavirus published in the New England Journal of Medicine, people with blood Type O, the most common blood type, are 35% less likely to get coronavirus while people who have blood Type A were “associated with” a 45% “higher risk of acquiring COVID-19”.

It is already understood that human blood group antigens can increase or decrease susceptibility to many infections by serving as receptors for bacteria, parasites, and viruses while several blood groups can modify the patients immune response to infection. For example in the case of populations living in endemic areas with malaria some genetic varieties of blood types show greater resistance to the disease.

Roy Silverstein, former president the American Society of Hematology and Chairman of the Department of Medicine at the Medical College of Wisconsin warns however that ‘Those who are not type A should not interpret this study to mean that they can let their guard down. Similarly, the data are not yet convincing enough to recommend that those with type A need to do even more than what is recommended.’

Other studies also suggest a statistical correlation between non-O blood type and a higher rate of infection or more severe disease.

While data is limited still - a Chinese preprint study that looked at over 2000 COVID-19 positive individuals reported that there was a higher infection and death rate in people with type A blood than the general population while conversely fewer individuals with Type O blood were infected than would have been expected statistically.
Additionally while it is still very early, preliminary data from 23andMe’s ongoing genetic study of COVID-19 in the 750,000 who participated in their study also points to differences in the susceptibility to the virus based on ABO blood type. Specifically the data suggests that O blood type appears to be protective against the virus by as much as 18% when compared to all other blood types.

Research is ongoing.

Who is at higher risk of more severe disease from COVID-19?

As you will read and hear over and over again those with the most severe health problems are at higher risk, as are the elderly, in terms of suffering more severe disease and higher mortality.

A list of the risk factors includes:

  • People aged 65 and older.
  • People who live in a nursing home or long-term care facility
  • People who smoke
  • People who are obese especially those with BMI of 40 or higher
  • People with chronic lung disease
  • People with moderate to severe asthma
  • People who have serious heart conditions such as heart failure
  • People who are immunocompromised whether it is due to:
    • Cancer treatment,
    • Organ or bone marrow transplantation,
    • HIV or AIDS if poorly controlled
    • Immunodeficiencies of various causes
  • Prolonged history of corticosteroid use
  • People with diabetes
  • People with chronic kidney disease and those undergoing dialysis
  • People with liver disease

As more clinicial information becomes available we will have more detailed information as to how each of these factors contributes to disease severity and outcomes

Are the risks different for people with type 1 and type 2 diabetes?

Less important than the type of diabetes are factors like the age of the patient, complications and other health issues and how well managed their diabetes is.

Those with a greater number and severity of diabetes-related health problems tend to have worse outcomes than otherwise healthy diabetics irrelevant of type.

I have diabetes and symptoms of Covid-19. What should I do?

If you feel like you are developing symptoms, call your doctor and have some additional information ready for him/her.

  • Your last glucose reading and more if possible
  • Have your ketone reading available
  • Be aware of your fluid consumption
  • List all your symptoms
  • Ask any questions to help better manage your diabetes

Is COVID-19 different from the seasonal flu for Diabetics?

Yes - COVID-19 is a more serious illness with a higher rate of death and complications than the seasonal flu in - not only diabetics but everyone.

Recommended safety precautions for people with diabetes are no different than for the flu with frequent hand washing, covering coughs and sneezes.

Do I need to worry about DKA (diabetic ketoacidosis) and Coronavirus?

Experience with diabetes has shown that when sick with a viral infection, people with diabetes do face an increased risk of diabetic ketoacidosis. This is significantly more common in Type 1 diabetes.

Furthermore due to challenges associated with fluid intake and electrolyte levels - both important in sepsis management - the complications can be significantly worse in diabetics suffering from ketoacidosis.

Do people with diabetes experience a higher rate of serious complications from COVID-19?

Simply said: yes. People with diabetes do face a higher chance of experiencing serious complications from CV19 and it is understood that generally not only do diabetics in general suffer more severe symptoms but the risk increases the more severe and poorly controlled the diabetes. This is due to the fact that these risk factors increase the probability of the patient having other diabetes-related complications such as heart disease. Additionally the diabetes also reduces the bodies ability to as effectively fight infections.

Are people with diabetes more likely to get COVID-19?

While diabetics are not more likely to get Coronavirus than the general population the issue lies in the fact that they face worse clinical outcomes.

Data from China, Italy and elsewhere suggests that people with diabetes had significantly higher rates of serious complications and death than people without diabetes.

It is also evident now that the more number and severe the number of comorbidities a patient has - the worse the outcome in terms of need for hospitalisation, complications and death.

Can Someone Who Doesn't Have Symptoms Spread the Virus?

A person can be infected and spread the Covid 19 virus to others even without having any symptoms. That’s why keeping people apart is one of the best ways to slow the spread.


How is Covid 19 spread?

It is now thought that the spread of Coronavirus occurs mainly through close contact from person-to-person with proximity, length of exposure and the indoors each increasing probability of transmission.

The role of people who have COVID-19 but are without symptoms is not fully determined but it is believed that they may in some cases be able to spread the virus. What we do know is that the size of the exposure can be a determinant of the severity of the disease in individual patients in addition to other risk factors (such as number and severity of health problems)

In spreading from person to person the mechanism is:

Respiratory droplets produced when an infected person coughs, sneezes, or talks can enter the lungs of uninfected individuals and pass the disease as the droplets land in the mouths or noses of people nearby- additionally the droplets may be inhaled into the lungs.

The virus spreads easily

One of the things that has made COVID-19 the global pandemic it is - is the fact that the virus spreads relatively easily. It is very contagious and can also continue to spread “sustainably” to new people.

The virus that causes COVID-19 is spreading more very easily between people than influenza for example but less so than measles.

The probability of spread increases with the more closely and the longer a person interacts with others.

Can you get the virus from a surface.

While not by any means the main way the virus spreads it may be possible that a person can get COVID-19 through touching a surface that has the virus on it and then transmitting that to their mouth, nose and rarely it is believed, the eyes.


I heard I can get sick from wearing a face mask because of Carbon Dioxide, is this true?

Generally, no. The myth that one can get carbon dioxide poisoning, or hypoxia, from wearing a face mask and breathing in your own expelled breath is unlikely. Non-medical face masks aren’t sealed to the face, therefore air and CO2 circulate in and out of the mask, and they’re typically not worn for a prolonged period of time.

There’s always an increased risk for anyone with a pre-existing underlying health condition, including anxiety, that may cause other symptoms, but in most cases these aren’t significant. If you have concerns about wearing a mask with your respiratory condition, check with your doctor.

For healthcare workers who do wear tighter fitting medical masks or respirators and wear them for a prolonged period of time, the risk may be higher, but they also receive additional training on this. If you’re wearing a medical mask or respirator, be sure to use it properly, to avoid any further health risks or concerns.

Can Covid 19 cause problems with pregnancy?

From what experts know so far, most people who get Covid 19 during pregnancy will not have serious problems. But problems can happen if the mother becomes seriously ill.

Pregnant women who get Covid 19 might have an increased risk of preterm labor and birth, when the baby is born before 37 weeks of pregnancy. This seems to be more of a risk in people who get very sick and have pneumonia. Preterm birth can be dangerous, because babies who are born too early can have serious health problems. So it is important to talk to your doctor, nurse or midwife about any symptoms or health concerns you have, even if they don’t appear to be related to Covid 19.

Are pregnant people at high risk for severe symptoms?

Experts don’t yet know a lot about Covid 19 and pregnancy. But so far, pregnant people don’t seem more vulnerable to the infection than others, nor do they seem to have a higher risk of serious problems (like pneumonia) than other people of similar age. Most people who get Covid 19 during pregnancy recover before having their baby.

What If I'm Pregnant?

If you’re pregnant and you have questions about Covid 19 , talk to your doctor, nurse, or midwife.