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  • Writer's pictureWilliam Miller, MD

Bivalent COVID Vaccine now available.

On August 31st, the FDA amended its emergency use authorization for both the Pfizer and Moderna COVID vaccines to now include a second component targeted specifically at Omicron. The vaccines will include the original component which targeted the original strain of COVID and still provides a fair amount of protection. The Pfizer vaccine is authorized for use as a booster to the original series in people aged 12 and older. The Moderna is authorized for ages 18 and up. Both shots are to be used as boosters, not as the original series and should be given at least two months after the last shot.

The reason that this is thought to be important is that the original vaccine had less effectiveness against the current Omicron variant. However, it is still quite effective at 68%. The new addition to the vaccines specifically targets the two most common subtypes of the Omicron variant, BA.4 and BA.5. These are causing most infections currently and are expected to remain the dominant subtypes through the upcoming winter months.

The side effect profile is the same for the new bivalent vaccines as it was for the original vaccines. That is to say that they are considered to be very safe. Of course, there are those that would contest this statement. However, this remains what is supported by valid science.

The current thinking by most public health authorities is that we will need to continue to get repeat booster shots for COVID for the indefinite future. This is because of our own immunity declining after vaccination or a COVID infection. Antibody levels begin to fall after about 3 months. However, that does not mean that there is no immunity, just perhaps less so. The problem with this figure is that circulating antibody levels do not necessarily correlate with immunity. After all, our body does not continue to produce any antibody at full steam forever. All antibody levels generally drift down to some lower level with time. Having said that, people can get a second case of COVID after an original infection. These infections are usually much milder as one would expect.

There is much debate over how often we will need to get booster shots moving forward. The expert opinions range from every 2 months (which in my opinion is extreme), to every 6 months to once a year. If the current variant does not change and continues to cause generally milder disease, it seems that twice a year is reasonable. If a person is at high risk due to age or other illnesses such as lung disease, then three times a year might be a better choice. As with all things medical, it is best to discuss this with your primary care provider. The bivalent vaccine is available now through most locations in Mendocino County that have been providing the previous vaccines.

CORRECTION: In the previous week’s article on polio, I stated that the countries of Pakistan, Afghanistan, and Nigeria forbid vaccination. It has been brought to my attention that this statement oversimplified the reality and is inaccurate. The Taliban in Afghanistan announced in October that they will allow polio vaccination by outside humanitarian aid organizations, however, will not provide the vaccinations through the government. In Pakistan, a new Prime Minister has recently been elected who supports polio vaccination and has meet with the Bill Gates as well as representatives from Rotary International and pledged his support. Both the Bill Gates Foundation and Rotary International have had long standing programs to support the eradication of polio through vaccination. In 2003, Nigerian clerics and government officials called for a boycott of the vaccine out of fear that it was laced with anti-fertility drugs and could cause cancer. This eventually led the WHO to declare that “Nigeria is the most significant generator of polio in the world”. In 2016, the Nigerian government reversed its stance due to a significant rise in new polio cases over the preceding 10 years. They allowed UNICEF workers to do a widespread polio vaccination program in their country. Because of the decade long boycott, Nigerian parents remained reluctant to accept the vaccine for their children, but this is slowly changing as personal stories of polio induced paralysis in children and adults have circulated.

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