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  • Dr Danielle Walker

Delta Variant Question (United States)

We have had several questions come in about the new Delta variant. We are still learning a lot every day, but here are the most common questions with short answers from the data we have available (U.S. perspective).

What is the delta variant?

Delta is a new variant of COVID-19. We first saw it in India and it only took a month to spread around the world. Currently 83% of new cases in the U.S. and 99% of cases in the U.K. are from Delta.

Is Delta more contagious?

Yes, Delta is more contagious than the original variant. The viral load, or how much virus you have in your body from the disease, is 1,000 times greater than the original. The more virus you have in your body the easier it is to infect others.

For every person who got the original strain of COVID-19, they were likely to spread it to 2.5-3 other people. For every person with Delta, they are likely to spread it to 5 other people! This is why we saw it multiply so quickly and move around the world faster than the original variant.

Is the Delta variant more severe?

Thankfully, the Delta variant does not seem to be more severe, but it is similar in severity to the original strain. It is very new, so we are still watching what happens.

When we look at death from Delta we have to look at it from a few angles. Globally it has a similar case fatality rate as the original strain (2-3%). In the U.S. we hope that it will be slightly lower because many of our vulnerable and older populations have been vaccinated. We may still see high case fatality rates in populations that have low vaccination rates. States with low vaccination rates such as Missouri, Florida, Arkansas, and Louisiana are now starting to see larger outbreaks and ICU rooms filling again. We will have a better picture of the U.S. case fatality rate from Delta within the coming weeks as death is not immediate after infection.

If I already had COVID-19 with the first wave am I protected from the Delta variant?

Unfortunately, this topic has been one of the unique challenges with this disease. It would be amazing if everyone who got COVID-19 had good levels of antibodies and protection like what we see with chicken pox, but unfortunately that is not what we have seen so far. Many studies have documented people declining in natural antibodies anywhere from 3-6 months after illness. I wish there was a fast and easy way to test all of the different types of antibodies so we could know who had lasting protection and who didn’t, but this is not a simple or feasible thing to do within communities. A couple studies have shown patients with antibodies at 6-8 months, but several studies have found natural antibodies to start decreasing then. We never use just one study as a justification, because we need to see the full picture of the good and the bad. Because there are discrepancies and enough studies have documented a decrease or loss of antibodies within months of illness, it is recommended that those who had COVID-19 get vaccinated to be protected from reinfection and any new variants. England Public Health (where Delta has been circulating slightly longer than the U.S.) suggests that natural immunity from infection has not been protecting against the new Delta variant.

Who is getting infected?

The majority of Delta infections are happening among unvaccinated populations. In the U.S. 97% of COVID hospitalizations are among those who are not vaccinated.

Do the vaccines work against delta?

Yes. Pfizer, Moderna, and J&J all have good protection against the Delta variant.

Pfizer- excellent protection (80-96%)

Moderna- still awaiting more data, but expected to be similar to Pfizer with excellent protection

J&J- moderate to good protection expected, but we’re waiting on data with larger sample sizes

Should we be worried?

There is always a balance to everything, and there will never be a perfect answer that satisfies everyone. There’s a balance between health, protection, the economy, education, and more.

We feel concerned for those who are unvaccinated and those with compromised immune systems who may not have as much protection against the disease. This disease is preventable, so we need to do what we can to protect all people.

Many people are trying to look at COVID as life or death and if the case fatality rate looks low enough then we must be ok. What many people are missing is the burden this disease brings with suffering after infection. Up to one third of people who get COVID will experience lasting symptoms weeks to months after the acute phase of infection. Some people have experienced neurological issues, heart damage, difficulty breathing, extreme fatigue, brain fog, anxiety, depression, and more. There is an entire new field in medicine emerging just to learn about and treat “Long COVID” for those suffering. If this virus continues to spread through our communities and upwards of one third of people infected get Long-COVID, then we need to consider what burden that will place on our health and economic systems with the cost of long-term care and loss of work. There is a balance because completely shutting down countries also places a burden on many systems. We need to weigh the risks on community levels since some communities are considered low- and some are high- risk, and then balance the appropriate prevention measures to protect those at risk for infection.

Another aspect to consider is the risk of more mutations. If we don’t unify to stop the spread of this disease then it has the potential (as we are seeing now) to continue to mutate. Right now, we have vaccines that protect us, and we don’t want to walk the longer path of living in a world where our vaccines don’t work.

Should we be concerned about kids and Delta?

One aspect of the pandemic we feel thankful for is that this is not a disease that is killing children at high rates. So far, the majority of children (without underlying conditions) with COVID-19 have had mild disease. Our concern with kids is not about severe disease or death, but it is the role they play in the chain of transmission. As long as this virus is allowed to spread then we allow it time to mutate and infect vulnerable populations. While kids are not at high risk for severe disease right now, they do carry the virus when infected and can pass it on to those who are at high risk, especially with how high Delta viral loads are with infection.

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