As a doctor, I know new information is coming in daily about COVID-19. By keeping up to date, you can make sensible decisions to help keep you and our family from becoming infected. Here's the latest information you need to know about COVID-19, from A to Z. You may find some surprising facts and new resources. The more you know, the more you can protect yourself and those you love. Read on, and to ensure your health and the health of others, don't miss these Sure Signs You've Already Had Coronavirus.1 A: AgeOlder people are more at risk of dying from COVID. Although the death rate is around 1% for the overall population, that rises to 3.6% for those over 60, 14% over 70, and 14.8% over 80, according to the COVID Evidence Service. Eight out of 10 COVID deaths in the U.S. have been in adults over 65.Anyone over 50 should take serious precautions to avoid the disease, especially if you have other risk factors such as obesity, diabetes, or heart disease.The CDC recommends that older people limit social contact as much as possible. If you decide to go out, take steps to prevent becoming infected: * Plan your trip. * Stay outdoors wherever possible. * Keep at least six feet from other people. * Wear a mask over your nose and mouth whenever you're meeting others indoors, taking public transportation, or in a place where social distancing is difficult. * Wash your hands before and after every visit.The highest risk is attending large gatherings where attendees are from households you don't know.2 B: Black and Ethnic Minority Groups (BAME)According to a recent review in The Lancet, in the U.S., Black people are 13.4% of the population but account for 28% to 70% of COVID deaths (depending on the state). In majority-Black communities, rates of COVID infection are three times than in mostly white communities.The reasons aren't well understood. The journal Current Problems in Cardiology recently reported that BAME groups tend to have higher levels of comorbidities such as high blood pressure, cardiovascular disease and diabetes. Black households are more likely to be overcrowded and have poorer living conditions. Whether there are any specific biological factors putting them at higher risk is unclear.3 C: Contact TracingIf you test positive to COVID-19, anyone you've recently been in close contact with is contacted. They're advised to self-isolate for 14 days to avoid passing on the virus. A "close contact" is anyone who has been within six feet of you for at least 15 minutes, in the two days before developing symptoms, or before obtaining a positive test result.Contact tracing is one of the key tools for controlling the pandemic. Considering that 80% of people with COVID-19 infection are asymptomatic, asymptomatic patients are as infectious as symptomatic patients, and one person may potentially infect 406 others in 30 days, contact tracing can prevent a huge amount of disease.Contact tracing is usually performed by trained health advisers. In the US, the government has recognized the need to increase contact tracing, and efforts are underway at a cost of more than $46 billion.4 D: DeathWhat's the overall chance of dying if you get infected with COVID-19?According to the journal Nature, scientists have established a calculation called the infection fatality rate (IFR). This is more complicated than you might think. Many cases are not reported, so it's impossible to know exactly how much of the population has been infected.The current IFR is 0.5% to 1%. This means that for every 1,000 people infected, 5 to 10 will die.This figure varies between countries and according to specific risk factors, including age, sex, and comorbidities such as obesity, diabetes, and heart disease.5 E: Epidemic (or Pandemic)What's the difference between an epidemic and a pandemic? * A local cluster of infections is called an outbreak. * An outbreak which affects a population or a community is called an epidemic. * An epidemic which spreads to many different countries is called a pandemic.(Here's a memory device: The word pandemic has the letter "p," like passport, because it's an epidemic that travels.)Previous pandemics have had huge death tolls. The influenza pandemic of 1918 killed 30 to 50 million people. The HIV/AIDS pandemic has killed 32.7 million. It remains to be seen what the final toll from COVID-19 will be.RELATED: COVID Mistakes You Should Never Make6 F: Financial CostThe COVID-19 pandemic may cost the world $82 trillion over the next five years. That's the prediction from the Center for Risk Studies at the University of Cambridge Business School. In the U.S. alone, it will cost between $550 billion to $19.9 trillion. Considering the history of previous pandemics, economists suggest the financial effects of COVID-19 will be felt for the next 40 years.7 G: Grasp the SymptomsCOVID-19 affects different people in different ways. Infected people have had a wide range of symptoms reported – from mild symptoms to severe illness. Symptoms may appear 2-14 days after exposure to the virus. People with these symptoms may have—or have had—COVID-19: * Fever or chills * Cough * Shortness of breath or difficulty breathing * Fatigue * Muscle or body aches * Headache * New loss of taste or smell * Sore throat * Congestion or runny nose * Nausea or vomiting * DiarrheaLook for emergency warning signs for COVID-19. If someone is showing any of these signs, seek emergency medical care immediately: * Trouble breathing * Persistent pain or pressure in the chest * New confusion * Inability to wake or stay awake * Bluish lips or faceCall your medical provider for any other symptoms that are severe or concerning to you.8 H: Hand HygieneProper handwashing is mandatory to control the spread of COVID-19. Follow the CDC handwashing recommendations.Quiz yourself: Here are five statements about handwashing. Are they true or false? * As long as you use soap, it doesn't matter how long you wash your hands. * If you use a hand sanitizing gel, it's just as good as handwashing for removing germs. * You must use very hot water to get rid of the most germs. * There's no real need to dry your hands. * Always use a hand dryer, not a paper towel.The answers are all false. You do need to wash your hands for 15 to 30 seconds to make sure you remove most bacteria and viruses. Soap and water are more effective than the recommended 60% sanitizing gel at removing bacteria and viruses. If water is too hot, it can dry out your skin, which can crack and make it more susceptible to infection. When hands are wet, they transfer bacteria and viruses more easily, so it is important to dry them. And finally: Air dryers can spread bacteria, so use paper towels instead.9 I: Immune Response Most people develop an antibody response to COVID-19 within 10 to 21 days of becoming infected. For people with mild infections, it may take four weeks. But sometimes, there seems to be no measurable antibody response at all.People with severe COVID-19 infection tend to produce the highest levels of antibodies. Even people with undetectable antibodies can recover from COVID-19 infection.Immunologists are concerned that the antibody response may not provide long-lasting protection, meaning there may be a chance you could become reinfected in the future. However, there have been no reported reinfections to date.10 J: JusticeAmerican Justice Department officials state that if you intentionally spread COVID-19, this could result in prosecution under US anti-terrorism laws. COVID is a biological agent, and transmitting it could be construed as using a weapon.RELATED: Everything Dr. Fauci Has Said About Coronavirus11 K: Kids' HealthChildren seem less likely to become infected with COVID-19, and when they do, the illness tends to be less severe.The Lancet recently reported a snapshot of COVID-19 infection in children and young people in the first three weeks of April 2020 in 25 European countries. In total, 582 people under 18 tested positive to COVID-19 infection. The most common age was 5. Sixty-two percent were admitted to the hospital, 8% to the ICU, and 4% needed mechanical ventilation. Four children died.Children's role in transmitting the infection is unclear. One Chinese study found zero cases of a child transmitting the infection to an adult. Another mathematical modeling study found that school closures would only reduce mortality from COVID by 2% to 4%. Now that schools are reopening, careful surveillance is underway.12 L: LungsCOVID-19 is a respiratory illness characterized by fever and a dry cough. The virus results in pneumonia, which can progress to severe acute respiratory distress syndrome (ARDS) and sepsis.Once inhaled, viral particles are transported deep into the lungs, where they cause intense inflammation. The alveoli—the tiny air sacs where oxygen is absorbed into the bloodstream—fill with fluid. This reduces your ability to take in oxygen, and you feel breathless. It's dangerous for your body to be low in oxygen, which affects the function of every organ. If this becomes severe, this condition is known as ARDS.Although most COVID-19 infections are mild, 15% or people will develop more severe lung disease and 5% require mechanical ventilation. Doctors worry that some people can develop long-term lung damage after severe COVID-19 pneumonia, called pulmonary fibrosis.13 M: Mental HealthCOVID-19 has taken a major toll on our mental health. In a recent meta-analysis published in the journal Globalization and Health, the authors reported the prevalence of stress (29.6%), anxiety (31.9%), and depression (33.7%) in people surveyed.Mental health conditions have important consequences for overall health. Stress has been shown to significantly affect mortality. Anxiety weakens the immune system and increases the risk of acquiring the virus.For more information, see the CDC's Coping With Stress page, which has links to many helpful websites and phone numbers.14 N: Nasal SwabTo be tested for COVID-19, you will usually be asked to have a nasopharyngeal (NP) swab taken. If the test is positive, the test is 98% reliable. If the test is negative, the reliability of a true negative test—meaning you are definitely not infected—is lower, between 71% to 98%. If you have symptoms and the test is negative, it may be a good idea to have the test repeated. For how to get a COVID test in the US, click here.15 O: OutbreakHow the COVID-19 virus was created is still not definitively known. Scientists think it originated in a Chinese wet market from a coronavirus found in bats. One theory is that the virus was transferred from a bat to a pangolin. The pangolin may also have been infected with a coronavirus, and the two viruses then shared genetic sequences. The new, mutated virus—COVID-19—could have been transferred to humans by inhalation of the animals' infected respiratory droplets, via the food chain, or through contaminated urine or feces. After the COVID-19 pandemic began, Chinese authorities ordered wet markets to close. They have recently reopened but are prohibited from selling wildlife.RELATED: I'm a Doctor and Here's When You Can Safely Keep Your Mask Off16 P: PreventionThere's no magic wand to make COVID-19 disappear. To beat the virus, we all need to work together and follow government advice, which is based on scientific opinion.The CDC and WHO have compiled the following recommendations: * Avoid large gatherings of people. * Stay at least six feet away from people you don't live with. * Wash your hands regularly with soap and water for at least 20 seconds, and dry your hands afterward. * If you're not at home and can't wash your hands, use a hand sanitizer containing at least 60% alcohol instead. * Use a mask to cover your nose and mouth whenever you're somewhere where social distancing is difficult (or example in a supermarket, or on public transportation). A cloth mask is sufficient. It does not need to be a specialized hospital mask. * Cover your face when you sneeze or cough using a tissue, and dispose of it in a waste bin. * Try not to touch your face. * Keep things you touch clean: door handles, the computer mouse, kitchen worktops, and light switches. * If you feel sick, stay away from others, and don't share any cooking or eating utensils or household items. * If you have COVID-19 symptoms, such as a cough and a fever, or have been in contact with anyone who has tested positive, go into quarantine right away.17 Q: QuarantineYou need to quarantine if you've been in contact with anyone who has recently tested positive for COVID-19. This means staying at home and keeping away from other family members for 14 days, until you're sure you're not infected. You should take your temperature twice a day.If the risk of having the infection is high, the doctor will advise you to go into isolation. This means staying in your bedroom and away from the rest of the family. You need separate eating utensils and, if possible, to use your own bathroom.18 R: RecoveryBased on data from Wuhan, China, WHO reports that most people with mild disease recover from COVID-19 within two weeks. For those with severe disease, this may be three to six weeks. About 5% of COVID patients require admission to ICU. If you need mechanical ventilation, overall survival is about 60%.Those discharged from ICU face a range of physical, mental, and social issues. Patients may remain breathless and have a chronic cough. They may have swallowing difficulties. They may be weak and lacking in energy. Some may have developed other medical issues such as pulmonary emboli or heart problems. Depression, anxiety, and PTSD are extremely common. This all requires rehabilitation and takes many months.There is mounting concern that some patients with severe COVID may develop pulmonary fibrosis, or scarring of the lungs. More research is required, but pulmonary fibrosis is a serious, irreversible lung disease.19 S: Social DistancingSocial distancing means keeping at least a six-foot distance between yourself and other people. Why six feet?Several studies have concluded that most exhaled respiratory droplets travel less than three feet, then fall to the ground. However, other studies have shown that smaller particles can travel about six feet, and coughing or sneezing can cause those droplets to travel much further distances. Breathing in a few virus particles is unlikely to result in infection. Precisely how much virus you need to breathe in to become infected (a.k.a. viral load) is not known.Outdoors, the virus is immediately affected by air temperature, humidity, wind, and air currents, so it dissipates rapidly. You are very unlikely to become infected outdoors. It's best to meet friends and family outdoors and stay outdoors whenever you can.20 T: TreatmentThere is still no cure for COVID-19. Researchers are desperately searching for a successful treatment. More than 2,000 clinical trials are underway.The RECOVERY Trial recently reported that dexamethasone, a powerful steroid, has been found to reduce deaths in those with the worst respiratory disease.On July 4, the WHO announced that trials of hydroxychloroquine and lopinavir/ritonavir in patients hospitalized with COVID-19 were being discontinued, as the drugs had been found to be ineffective.In the UK, a trial is underway on an inhaled interferon beta (IFN-β). This is a protein produced in the body which plays an important role in the immune response and helps prevent viral replication.Some encouraging results are emerging for the drug remdesivir. This is a broad-spectrum antiviral previously used to treat hepatitis C. In patients with severe COVID, initial results with remdesivir suggest faster recovery times compared to placebo.RELATED: I'm an Infectious Disease Doctor and Would Never Touch This21 U: Update: Second PeakThe Daily Telegraph recently reported statistics about countries now experiencing a second peak of COVID-19 infection. Some countries which have come out of lockdown have had to reinstate those measures. * In Victoria, Australia, the increase coincides with the start of the Australian winter, a time when seasonal flu is usually also on the rise. * In Israel, a second peak has been attributed to coming out of lockdown too quickly. * In Iran, experts believe the second peak is due to non-compliance with social distancing rules. * In Saudi Arabia, the second peak is attributed to the rich/poor divide. The virus is mainly spreading in poor immigrant workers. * In Japan, 70% of new infections are in younger people, who frequent clubs, restaurants, and bars.In the USA, the infection curve looks very different. As the initial numbers of cases continue to rise, it does not yet appear to have passed the first peak. There are fears for how the US will fare this winter if the virus is still spreading uncontrolled. Social distancing seems vital for control of the infection.22 V: VaccineTo date, 140 COVID-19 vaccines are at various stages of development, and 13 are being tested in human trials. While many of us have pinned our hopes on a successful vaccine, we need to accept that this may never be achieved.First, COVID-19 is a coronavirus. The common cold is caused by many coronaviruses. We know that in general, coronavirus infections do not result in long-lasting immunity. This means people can be re-infected. There has never been a successful vaccine for the common cold.Second, scientists have been unable to produce a vaccine for the coronaviruses that cause Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS), which caused lethal outbreaks in 2003 and 2012 respectively.23 W: What Is the R-Value?R is a measure of how many people will become infected if one person has the virus. * If R is 1, this means the outbreak is standing still. * If R is greater than 1, the virus is spreading more rapidly. * If R is less than 1, the virus is dying out.Data from the initial outbreak of COVID-19 in Wuhan, China, suggested an R of 5.7. In the UK on June 19th, the government reported an R of 0.7-0.9. At this level, viral spread is thought to be under control.In the USA, R values for each state were published on July 9. R varies between 0.85 in Connecticut to 1.36 in Montana.24 X: XX ChromosomesEarly in the pandemic, New Scientist reported that men were more likely to get severe COVID infection and to die from it.In December 2019, The Lancet described the first 99 people admitted to hospital with COVID-19 in Wuhan, China. Twice as many men were admitted as women, and 75% of deaths were in males.The exact reasons for this are still not entirely clear. However: * The genes for the immune response are on the X chromosome. (Women have two X chromosomes and men only have one.) * In China, male smokers far outnumber female smokers. Only 5% of women smoke. Smokers are more susceptible to COVID-19 infection. * Women's bodies produce estrogen and progesterone, which may have a positive effect on the immune system. * Men may be less hygienic than women, the study authors suggested.25 Y: YouCertain risk factors make you more susceptible to being infected with COVID-19 and having a more severe infection. * Age: Risk increases with advancing years. In the UK, retirees are 34 times more likely to die from COVID-19 than people of working age. Almost one-third of UK COVID deaths have been in people living in residential care homes. * Medical conditions: The following conditions increase your risk of contracting COVID: Obesity, type-2 diabetes, heart disease, chronic obstructive pulmonary disease (COPD), kidney disease, sickle cell disease, and being immunocompromised.Some other medical conditions may also be significant, but the evidence is less strong (e.g. asthma, pregnancy, and smoking). For a list of these medical conditions, visit the CDC website.If you have any of the risk factors on this list, follow the advice about how to protect yourself even more carefully.26 Z: Zip CodeSearch for COVID details in your area by using the CNN COVID zipcode tracker.The CDC also publishes a COVID data tracker.You can track COVID cases around the world using Worldometer.And to get through this pandemic at your healthiest, don't miss these 35 Places You're Most Likely to Catch COVID.Dr. Deborah Lee is a medical writer at Dr Fox Online Pharmacy.