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This is a  Q and A column written by Dr. Lydia S. Segal, M.D. in conjunction with Chaffee County Public Health. This column is focused on questions readers have about COVID-19 news and sciences.  As Segal points out, ‘Everything I write today is valid for today. COVID-19 news and science are rapidly evolving, assume updates will be made”

Since the beginning of September, reader’s questions have been focused on vaccine effectiveness against the Delta variant, booster eligibility, and mask effectiveness. Next week I will address COVID and children: masks, vaccines, and general safety.

QUESTION: How effective are the current vaccines against the Delta variant?

ANSWER:  The CDC just released three studies, which in total consisted of more than  600,000 people who had COVID-19 in the USA from April to July. These well-executed and scientifically sound studies unequivocally demonstrated the effectiveness of the three approved vaccines against the Delta variant. They looked at urgent care/ER visits, hospitalizations, and deaths. Keep in mind that vaccines are designed to prevent illness but not infection. In Chaffee County, the breakthrough rate is less than one percent of those fully vaccinated based on the county and state COVID dashboards.

Lydia S, Segal, MD, MPHAt the national level, compared to vaccinated people in the USA, being unvaccinated increases your chance of getting the disease by 4.5 times. In-patient hospitalizations are ten times higher and COVID-related deaths were eleven times higher in the unvaccinated compared to the fully vaccinated.

The vaccines were originally tested last summer on about 40,000 people when the original (now called Alpha) variant was prevalent in the USA. At that time, it was found that the two-shot series mRNA vaccines, Pfizer and Moderna, were about 95 percent effective against people getting COVID. The single-shot J&J  vaccine was found to be about 85 percent effective against severe disease.

Now, because of the Delta variant, the comparable effectiveness from the earlier trials looks to be about 80 percent for Pfitzer and Moderna. There is no current, reliable data on the change in the effectiveness of the J&J vaccine against the Delta variant but it is assumed it also decreased in its effectiveness.

The decrease in effectiveness against the Delta variant is currently thought to be attributable to three causes: waning vaccine immunity over time (which is common in all vaccines); decreased public adherence to mitigation measures like masking and social distancing; and the nature of the Delta variant being more transmissible.  It is not yet clear if one of these three theories is predominant or if they all play their part in lessening effectiveness.

Keep in mind the vaccines are all still highly effective in preventing serious cases of COVID requiring hospitalization or resulting in death.

QUESTION:  A reader asks about boosters. What is a booster?  And why might I need one?  

ANSWER:  As stated above, because immunity wanes with time, it has been thought that a booster might increase antibodies and other components of the immune system to help fight off COVID, especially in severe cases requiring hospitalization. This is particularly true of those over 75 years of age with pre-existing medical conditions and those who are immunocompromised.

The question as to whether the general population needs a booster is still being reviewed by members of the FDA and CDC. Data analysis is expected to be completed by the end of this month.

QUESTION:  Is the booster different from the previous vaccines?

ANSWER: Currently, the booster is the same as the previous shots you would have gotten. This past summer there was talk of a Delta variant-targeted booster, but to date, none of the three USA-approved vaccine makers has issued a press release about such a specialized vaccine booster. It would take development time, testing time, and data analysis review time before such a booster is released.

QUESTION: Why did President Biden issue a vaccine mandate last week?

ANSWER:  Due to the low rates of vaccination in the U.S., and in an attempt to encourage the population to get vaccinated, President Biden issued a vaccine mandate that applies to all federal employees and contractors as well as to those working in companies that employ over 100 people. He stated that unless more people were vaccinated we would continue to have ongoing COVID-related illnesses and deaths.

For more information about COVID and the vaccines, eligibility and appointments, see the links below. Pharmacies are getting small shipments of vaccines. Information will be posted online here and on the county public health and hospital web pages.

If you have questions you would like Dr. Segal to address in a future COVID Q and A column, please write to

Public vaccination information:

Pharmacies with vaccine clinics:

Salida:  Safeway, Walmart and Salida Pharmacy

Buena Vista: Mt Shavano (LaGree’s), City Market, BV Drug and Valley-Wide Health,

By Lydia S. Segal, M.D., MPH