I am following the latest developments on COVID-19 and our efforts to control the pandemic. I will update this page regularly, so if you are interested, check back often. As of October 20, 2021:

Family Herd Immunity: To stop this pandemic of COVID-19 with herd immunity, more than 80 percent of the world’s population would have to be vaccinated or have had the disease. However, having even one member of your family immunized will help to protect you from getting the disease and possibly dying from it. A study of 1,789,728 people from 814,806 families in Sweden (JAMA Internal Medicine, October 11, 2021) found that:
• Family members without immunity had a 45-97 percent reduced risk of contracting COVID-19 as the number of immune family members increased.
• In families with two people living together, having one of them immunized reduced the rate of infection in the other person by 45 percent.
• In two to five-member families, each additional immunized person reduced the rate of infection in the non-immunized members dramatically.
• In five-member families, having four members immunized reduced the chances of the fifth member developing an infection by 97 percent.

Long COVID Syndrome: More than half of the 236 million people diagnosed with COVID-19 worldwide can be expected to suffer from Long COVID Syndrome, with symptoms lasting for six months or longer (JAMA Network Open, October 23, 2021;4(10):e2128568). Researchers conducted a review of 57 studies that included 250,351 unvaccinated adults and children diagnosed with COVID-19 between December 2019 and March 2021. The participants in these studies had an average age of 54, and 79 percent had been hospitalized. Symptoms of long COVID syndrome can include weight loss, fatigue, fever, pain, decreased mobility, difficulty concentrating, anxiety, abnormal chest X rays, shortness of breath, chest pain, palpitations, hair loss, rashes, stomach pain, loss of appetite, diarrhea and/or vomiting.

Booster Doses for Pfizer and Moderna: Advisors to the Food and Drug Administration (FDA) voted unanimously to approve Moderna or Pfizer booster shots for people over 60 or with underlying health problems, or those with jobs or living situations that put them at increased risk for exposure to COVID-19 (FDA Briefing, October 14, 2021).

J&J Recipients Get Better Booster Response from Moderna or Pfizer: An NIH study compared the response to booster shots with the same or different vaccines than were received from their first shots from Pfizer, Moderna, or Johnson & Johnson, the three COVID-19 vaccines currently authorized in the U.S. (MDRXiv, October 14, 2021, not yet peer reviewed). The study found that using different vaccines as boosters appears to induce the same or increased antibody response, compared to using the same booster dose. People who had received the J&J single-dose vaccine and then received a Moderna booster had antibody levels rise dramatically higher than those who received a J&J booster. Mixing and matching booster shots of different vaccines appears to be safe, and this week the FDA is expected to start allowing people to receive a different vaccine as a booster than the one they initially received (New York Times, October 18, 2021).

Unlikely to Get COVID-19 from Contaminated Surfaces: A study from Canada found that your chances of getting COVID-19 from surfaces at the grocery store are very low. Researchers cultured surfaces for COVID-19 at four grocery stores for a month and had no positive cultures (Current Research in Food Science, Oct, 2021;4:598-602). They cultured handles of grocery carts, payment terminals, conveyor belts, deli counter surfaces and plastic and metal handles in frozen food sections. This study refutes earlier studies that found the virus on shopping carts and freezer doors. It does not show that the virus cannot live on surfaces, and suggests that following the rules such as sanitizing surfaces and wearing masks can help to keep the surface areas of grocery stores relatively free of COVID-19 virus. It now appears that COVID-19 is primarily a disease that is acquired from breathing virus-infected droplets indoors in places where lots of people congregate.

Differences in COVID Antibody Responses in Natural Infection Versus Vaccination: Both natural COVID-19 infections and vaccinations help to protect you from infections by causing you to produce:
• antibodies that bind to the virus, and
• protective memory B cells that can help you to make antibodies if you are infected later on.
Having an infection with COVID-19 appears to be more effective in giving you memory B cells that can continue to make antibodies for more than a year afterwards (Nature, Oct 7, 2021). Both vaccination and natural infection caused similar increases in memory B cells. After six months, a vaccinated person starts to lose memory B cells, so their body could then lose its ability to make protective antibodies. One year after having been infected with COVID-19, recovered patients continue to make new and potent memory B cells. However, the virus that causes COVID-19 can still cause disease if you are infected in the future, so it is safer to get the vaccination than it is to get an infection with COVID-19. Memory B cells for smallpox have lasted at least 60 years after vaccination, and those for Spanish flu may last for 100 years.

As of October 10, 2021:

Booster Doses Six Months after 2nd Pfizer Vaccination: Six to 18 months after you receive your second dose of the Pfizer vaccine, you may still be at risk for developing COVID-19, but you are highly protected from getting serious disease that can result in hospitalization, intubation and death. The CDC recommends a third booster dose of the Pfizer vaccine for people over 65, those with immune-compromising health conditions and those in high-risk environments.  Similar recommendations are expected soon for Moderna and J&J vaccine boosters. In my opinion, anyone who is concerned about his or her immune status should get a booster shot.

Six months after the second Pfizer COVID-19 vaccination, antibody levels and immunity drop significantly, even though the vaccinated person is still protected from serious disease. In a study from Quatar, six months after second vaccination 20 percnt were protected from disease and almost 100 percent were protected from serious disease, hospitalization and death (NEJM, October 6, 2021) . An Israeli study showed that protective blood antibody levels drop significantly six months after the second Pfizer immunization (also in NEJM, Oct 6, 2021).

When a virus or vaccine enters your bloodstream, your immunity produces antibodies that try to attack and kill the virus. However, antibodies have a limited lifespan and eventually disappear from your bloodstream. Both vaccinations and infections cause your body to produce memory B cells that can last for a lifetime, so the next time that virus tries to enter your cells, the memory B cells quickly respond by stimulating your immunity to produce large amounts of antibodies that try to kill that virus. Memory B cells for the Spanish flu are still present 100 years later and those for smallpox last more than 50 years.

Vaccinations produces greater amounts of circulating antibodies than natural infection, but the live virus that causes natural COVID-19 infections stays around in your bloodstream for a longer period of time than the vaccination and produces longer-lasting and more-potent memory B cells that can produce antibodies many years later. However, a natural infection can hospitalize and kill you, while vaccinations almost never do that (Nature, October 7, 2021)

Older entries can be found in the post titled Latest on COVID-19: Archive