Coronavirus Disease (COVID-19)

Symptoms and Causes

What are the symptoms of COVID?

People with COVID can experience a wide range of symptoms, from mild to severe. Some people have no symptoms at all. The most common of these include fever, dry cough, shortness of breath, muscle aches, and fatigue. Other symptoms, such as nausea, diarrhea, lack of smell or taste, rashes, and headache are also seen. After exposure, symptoms typically start within five days, but they can sometimes take up to 14 days to appear.

Some people have severe or life-threatening symptoms and require hospitalization. While severe COVID is more common in older people or people with underlying medical problems, even young, healthy people can develop severe disease.

Sometimes after COVID infection, people develop long-term symptoms, including persistent fatigue, depression, shortness of breath, or weakness, sometimes called “long COVID” or “post-COVID conditions.” This is more common after people have had severe COVID, but it can be seen even with mild cases of COVID. We’re still learning more about how common this is, what it can look like, and how best to help people who are experiencing persistent symptoms after COVID infection.

How does COVID spread?  

COVID spreads mainly through small droplets and particles that are released when an infected person breathes, coughs, or sneezes on or talks to another individual nearby (or within six feet).

Rarely, the act of touching contaminated surfaces and then touching one’s mouth, nose, or eyes can spread the virus.

Anyone with COVID can be contagious, and about 20% of infected people do not show any symptoms or may not have developed symptoms yet.

Delta, Variants, and Boosters

What do I need to know about variants?

The more a virus spreads, the more chances it has to replicate, and the more likely small replication errors are to occur. These “errors” are called mutations, and they change how the virus is structured.

When a virus with a mutation successfully replicates and spreads (typically because that mutation is favorable to the virus), it’s called a variant. Sometimes, as with the Delta variant, mutations can make viruses more contagious and potentially more dangerous in the body.

How do vaccines relate to variants?

Because vaccines are developed based on existing knowledge of how a virus is structured, as a virus mutates, vaccines can be less effective against certain variants and some vaccinated people may contract that variant. This is not a reason to skip the vaccine. Rather, it’s a big reason to get it. The more people who are vaccinated, the less a virus can spread (because, remember, the vaccine still protects most people) and the less the virus will continue to mutate.

Currently, 97% of COVID hospitalizations (most of which are now due to the Delta variant) are among unvaccinated people, which is a sign that the vaccines still work remarkably well when it comes to preventing severe illness. In addition, from what we know, the vaccine is still effective against all the variants that have thus far been identified. But to keep blocking existing mutations and preventing future ones, getting more people fully vaccinated is key.

What are breakthrough cases and how worried should I be?

Breakthrough cases refer to when someone who is vaccinated is infected with COVID. These are to be expected because no vaccine is perfect. Breakthrough infections may occur because a variant has become good at evading the vaccine, because an individual may have a suppressed immune system so the immunity conferred by the vaccine is less protective, or because the strength of the vaccine wanes over time.

Importantly, not only do breakthrough cases only occur in a small percentage of those vaccinated, but they also tend to be much milder. In data collected from 24 states at the end of July, only 1.7% COVID cases were among fully vaccinated people. Moreover, data from the Kaiser foundation found that only 1 in 17,000 breakthrough cases led to hospitalizations. Lastly, research shows that those who experience breakthroughs are sick (and contagious) for shorter periods of time.

This being said, data from Pfizer shows waning vaccine effectiveness after six months and, indeed, the number of breakthroughs (and their severity) are slowly going up as more people are reaching that benchmark.

Also, even if you have a mild or asymptomatic breakthrough case, you can still pass the virus on, which is important to know if you’re spending time with unvaccinated people (such as children under 12)—or those who are older or immunocompromised as population-wide immunity begins to decrease.

What do I need to know, specifically, about the Delta variant?

The Delta variant is currently the most common COVID strain in the US. This variant appears to be two-to-three times more transmissible than the original COVID strain. For context, those infected with the original COVID strain were believed to typically infect about three other people, while those with Delta are believed to infect closer to seven.

It’s unclear if Delta also makes people sicker, though there is some circumstantial evidence—including higher rates of hospitalization among children—that have led some experts to speculate that it may. The Delta is now the most common COVID strain in the US.

Symptoms of Delta largely resemble those of other COVID strains, though they may also be more similar to that of a cold, including congestion, sneezing, fever, body aches, and sometimes a cough. Loss of taste or smell is less common in Delta infections.

What should I know about booster shots?

Because data is showing that vaccine effectiveness wanes over time and that booster shots significantly improve immunity, as of August 2021 Pfizer or Moderna booster shots are now being offered to moderately-to-severely immunocompromised individuals including cancer patients, those who have had recent transplants, those with certain autoimmune conditions and more (for a complete list, see the CDC website).

For this same reason, beginning September 20, the Biden administration will be administering booster shots to anyone for whom eight months or more has passed since their last COVID vaccination. The rollout will begin with healthcare workers, those in nursing homes, and the elderly. So far, this only applies to those who received Pfizer or Moderna shots, but guidance for those who received Johnson & Johnson is expected shortly.

Will the flu be circulating, too? Should I get a flu shot this season?

In short, yes. The CDC continues to recommend flu vaccines this season, and COVID does not mean that the flu won’t be circulating, too. It’s worth noting, in particular, that one suspected reason for last year’s drop in flu cases was increased masking and quarantining.

This year, by contrast, many of us will be going back to in-person work or school, so it’s reasonable to assume that the flu picture will look different. As a positive byproduct of getting a flu shot, a recent study showed that individuals who had received the flu shot had fewer health complications connected to subsequent COVID infections.

Treatments for COVID

What do I do if I have symptoms of COVID?

The first step is to reach out to Galileo or your healthcare provider. We can help you with supportive care to help you feel better. Some people will need treatment, and getting treatment as soon as possible means that it can be more effective.

One treatment, Paxlovid, is available in a pill form. It can be very effective to keep high-risk people out of the hospital and can reduce the chance of death from COVID, but it needs to be started as early as possible.

Because you can spread COVID to others, we recommend isolating at home and from others in the household for at least 5 days. During this time, if you must be around others, you should wear a high-quality, well-fitting mask. Refer to CDC guidelines for current information on when to end isolation and information on how to keep others healthy.

Distancing and Masks

Why does standing at least six feet apart (and outside) help? Why did we have to do that?

Staying at least six feet apart from other people (social distancing) reduces the risk of exposure to respiratory droplets released from an infected person.

Outdoor spaces are safer than indoor ones, because there’s usually more room outside for people to social distance. Outside, there’s also often better ventilation, which prevents viral respiratory droplets from lingering in the air.

Currently, because of vaccination and lower rates of circulating COVID, social distancing is no longer required in most settings. However, if another, more dangerous variant develops, or if there’s a significant rise in COVID infections to the point where hospitals are over capacity, we may be asked to reinstate social distancing.

How do masks work?

Masks work by protecting the wearer from inhaling viral respiratory droplets and preventing an infected individual from spreading the virus to others. Currently, masks are recommended for people who have COVID for 10 days after their symptoms have started.

I’m vaccinated. Should I be masking?

While vaccination is good at preventing severe disease, breakthrough infections are common at this time, and no infection is zero-risk. Masking can be a valuable tool to help keep you and others safe, particularly if you’re at high risk or you have a COVID infection.

Some people also choose to wear a mask when in crowded areas since the vaccination status of those around is unknown.

Vaccination and Antibodies

How do the vaccines work?

As of March 2023, there are four vaccines that have been granted approval for emergency use by the FDA in the United States.

Two of these vaccines (Pfizer and Moderna) are known as messenger RNA vaccines. These work by teaching the recipient’s cells how to make a harmless piece of the COVID virus, without giving the recipient COVID. This prepares the person’s immune system to fight against future infection. To be effective, the Pfizer vaccine requires two doses, three weeks apart, and the Moderna vaccine requires two doses, four weeks apart.

The third vaccine (Johnson & Johnson/Janssen) is a viral vector vaccine. It uses a modified version of a non-COVID virus (adenovirus) as a vector to teach the recipient’s cells how to make a harmless piece of the COVID. As with the messenger RNA vaccines, this does not give the recipient a COVID or adenovirus infection. This vaccine only requires one dose to become effective, but overall, it’s not used as a first choice because of a rare risk of a potential complication.

The fourth vaccine (Novavax) is a protein subunit vaccine that looks like the spike protein on the coronavirus. The immune system will learn to respond to that protein so that if you’re exposed to COVID, you’ll develop an immune response.

Why do I need a booster shot?

Currently, the US recommends being fully vaccinated and boosted. This helps people develop the strongest immune response, reduces individual risk, and reduces the risk of dangerous variants developing.

Vaccination and boosters are especially important for anyone who is older or immunocompromised.

Are COVID vaccines safe?

The vaccines have been extensively tested for safety. While side effects of a fever, fatigue, or headache are fairly common, the side effects are mild and only last a short time.  If you have a history of a severe allergy to any component of the vaccine, you should discuss this with Galileo or your healthcare provider to help you choose the best approach for you.

There are some rare complications reported with the vaccination, such as myocarditis/pericarditis (an infection in or around the heart) or blood clots. However, the risk of the vaccine is significantly less than the risk of a complication from a COVID infection.

The Johnson & Johnson vaccine had slightly higher rates of a rare side effect and is not considered a preferred vaccine at this time.

I got the Johnson & Johnson vaccine. Should I be worried?

In short, no. In April 2021, it was discovered that an extremely small number of people who got the Johnson & Johnson vaccine were at risk for blood clots with low platelets (thrombosis with thrombocytopenia syndrome or TTS). Among women 18 to 49, the frequency was 7 in 1 million vaccinated. For women 50 years and older and men of all ages, this adverse event is even more rare.

In June 2021, the FDA reported another very rare side effect: an increased risk of a neurological condition known as Guillain-Barré syndrome (this syndrome has also been seen in COVID patients). Only 100 cases (mostly among men) were identified among the 12.8 million patients who received the Johnsons & Johnson vaccine.

For both side effects, they both tend to occur soon after vaccination (for blood clots, within days, and for Guillain-Barré, within two weeks), and treatments are available for each. So if you were vaccinated some time ago, data suggests you have nothing to worry about.

The Johnson & Johnson vaccine is still available, because the FDA has deemed that its benefits still far outweigh these small risks. But if you are unvaccinated and the risks worry you, you can receive a Pfizer or Moderna shot instead.

What are the typical side effects?  

As with any vaccine, everyone can react differently. If you have side effects, this is a normal sign that your body is building protection against the virus. Common side effects include pain, redness and swelling in the arm where you received the vaccine, headaches, fevers, chills, muscle aches, nausea, and fatigue.

Typically these side effects will go away after a few days. Serious side effects, such as severe allergic reactions, are extremely rare and typically occur in those with a history of severe allergies. After receiving the vaccine, you’ll be monitored closely for 15 minutes. If you have a history of severe allergies, you’ll be monitored for at least 30 minutes.

After I’m vaccinated, how long am I protected from COVID infection?

We see an increase in protection within about 10 days after completing the initial series of any of the vaccines. The amount of time that you’re protected varies quite a lot, based on the virus mutations and your response to the vaccine.

With more vaccinated people, there's a lower chance that the virus will find a way around the vaccine. It's likely that the antibodies will wane with time, but we are still learning about how this works and how often people will need to be revaccinated.

If I have antibodies, am I immune? Can I pass COVID to others?

Unfortunately, it’s possible to have COVID more than once. Most people do not develop a second COVID infection within about 90 days after having had it.

Because there are many different COVID variants circulating worldwide, it’s possible to get infected with a second strain, even after you’ve had a COVID infection. Having antibodies against COVID does suggest some protection against reinfection, regardless of whether those antibodies come from having had COVID or from vaccination.

We’re still learning about reinfection and about how to protect ourselves from repeat infections.

Do I need to get vaccinated if I’ve already had COVID?

Because there are so many different variants of COVID, vaccination is still necessary, even if you’ve had COVID before.

Vaccines reduce the severity of COVID infection, making vaccinated people less likely to be hospitalized or die from a COVID infection. They may also reduce the risk of spreading it to others.

Will the flu be circulating, too? Should I get a flu shot this season?

In short, yes. The CDC continues to recommend flu vaccines. COVID and the flu will be circulating at the same time, and getting vaccinated will help keep you and others safe.

Variants

What do I need to know about variants?

The more a virus spreads, the more it replicates. Each time a virus replicates, there’s a chance for replication errors to occur. These “errors” are called mutations, and they change how the virus is structured.

When a virus with a mutation successfully replicates and spreads, it’s called a variant. Sometimes, as with the Delta variant, mutations can make viruses more contagious and potentially more dangerous.

How do vaccines relate to variants?

Vaccines are developed based on existing knowledge of how a virus is structured. As a virus mutates, vaccines can be less effective against certain variants. This means that some vaccinated people may contract that variant.

This is not a reason to skip the vaccine. Rather, it’s a big reason to get it. The more people who are vaccinated, the less a virus can spread (because the vaccine still protects most people) and the less the virus will continue to mutate.

Currently, most hospitalizations are among unvaccinated people, which is a sign that the vaccines still work remarkably well when it comes to preventing severe illness.

What are breakthrough cases, and how worried should I be?

Breakthrough cases refer to when someone who is vaccinated becomes infected with COVID. Because no vaccine is perfect, breakthrough infections are expected. Importantly, breakthrough cases only occur in a small percentage of those vaccinated, and the infections tend to be much milder.

Breakthrough infections can occur because a variant has become good at evading the vaccine, an individual has a suppressed immune system (so the vaccine is less effective), or the strength of the vaccine wanes over time.

Even if you have a mild or asymptomatic breakthrough case, you can still pass the virus to others. This is important to know if you’re spending time with unvaccinated people or those who are older or immunocompromised.

Related Content & Links

Frequently asked questions about COVID-19 (CDC)

Comparison of current COVID-19 vaccines (AAFP)

Find out where/how to get vaccinated in your area (Vaccine Finder)

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