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The 7-day average of COVID-19 infections declined to around 10,600 in early July, leading many to believe the United States was on the homestretch of defeating the pandemic. But since that time, the emergence of the Delta variant has caused infections to rapidly increase.

The 7-day average in early August is around 80,000, representing a 148% rise in new coronavirus infections.

An internal document from the Centers for Disease Control & Prevention (CDC) was recently made public by The New York Times, and it contains important details about the Delta variant.

Here is what we know as of early August 2021.

Transmissibility

Part of the reason the original strain of COVID-19 (Alpha strain) was considered so dangerous is that it is easily transmissible from person to person.

With the new Delta variant, the CDC found that it’s even more contagious than the Alpha strain and it appears to be responsible for most new infections. In fact, the CDC recently found that more than 80% of new cases in the U.S. were caused by the Delta variant.

The CDC’s report compared the level of contagiousness to chickenpox, a disease that used to be very common in the United States. Thanks to the chickenpox vaccine, more than 3.5 million cases of chickenpox, 9,000 hospitalizations, and 100 deaths are prevented in the U.S. each year.

Delta Symptoms

The symptoms associated with the Delta variant appear to be the same as with the original Alpha strain. These include: fever or chills, cough, shortness of breath or difficulty breathing, fatigue, muscle or body aches, headache, and new loss of taste or smell, among others.

But more importantly, research found that the Delta variant grows more rapidly and to higher levels in the respiratory tract, making severe symptoms more likely for unvaccinated people. While vaccinated people will likely be asymptomatic or have very mild symptoms from the Delta variant, it is also possible for them to spread the disease.

Vaccination Rates

The CDC has consistently said that widespread vaccinations are the key to ending the pandemic. As of early August, about 67% of the U.S. population aged 12 and older had at least one dose of a vaccine. These rates vary significantly between states, with the highest being Vermont at nearly 87%, and the lowest being Mississippi at 50%.

With the Delta variant spreading rapidly, more people are choosing to be vaccinated. For example, in Mississippi, the 7-day average of people receiving a first dose was 5,203 on July 27th, more than triple the average from July 1st.

Breakthrough Infections

The term “breakthrough infection” indicates the rare occurrence of a vaccinated person becoming infected with the Delta variant. At present, approximately 0.04% of vaccinated people tested positive for COVID-19.

When a vaccinated person tests positive, most either have no symptoms or have very mild symptoms. Their symptoms are more like those of a common cold, such as cough, fever, headache, and the addition of significant loss of smell.

It’s important to note that the vaccines are highly effective in preventing serious illness, hospitalization, and death.

Masking

With the Delta variant surging, the CDC’s data suggest that all people with weak immune systems should wear masks. They recommend the same for vaccinated Americans who are in contact with young children, older adults, or otherwise vulnerable people.

The CDC recommends that masks be worn indoors in areas where virus transmission is high, even for those who are fully vaccinated.

Some businesses have returned to mask recommendations for indoor settings, and a few states have reinstated mask mandates.

Lockdowns

Despite the surge in new infections, widespread lockdowns are unlikely according to Dr. Anthony Fauci, the nation’s leading infectious disease expert.

Dr. Fauci says the large numbers of vaccinated people can help prevent the level of hospitalizations we saw last winter. He also cites continued vaccinations as essential for preventing further infections, variants, and lockdowns.

Ventilation

For information on how mechanical ventilation impacts the spread of COVID-19, check out this recent article on the AprilAire blog.