WHO Reports Breakthrough Monkeypox Cases, Says Vaccines Are 'Not a Silver Bullet'

Health officials say that while the monkeypox vaccine is not 100% effective, people can also use preventive measures to decrease the risk of transmission

This 2003 electron microscope image made available by the Centers for Disease Control and Prevention shows mature, oval-shaped monkeypox virions, left, and spherical immature virions, right, obtained from a sample of human skin associated with the 2003 prairie dog outbreak. Monkeypox, a disease that rarely appears outside Africa, has been identified by European and American health authorities in recent days.
Monkeypox virions. Photo: Cynthia S. Goldsmith, Russell Regner/CDC via AP

The World Health Organization (WHO) has revealed there have been a number of breakthrough cases of monkeypox after preliminary reports detail the efficacy of the vaccine.

In a press briefing, Dr. Rosamund Lewis, WHO's technical lead for monkeypox, discussed reports of breakthrough monkeypox cases in people who received a prophylaxis vaccine following exposure to the virus.

"We have known from the beginning that this vaccine would not be a silver bullet, that it would not meet all the expectations that are being put on it and that we don't have firm efficacy data or effectiveness data in this context," Lewis explained.

"The fact that we're beginning to see some breakthrough cases is also really important information because it tells us that the vaccine is not 100% effective in any given circumstance, whether preventive or post-exposure," she continued. "We cannot expect 100% effectiveness at the moment based on this emerging information."

Monkeypox can be prevented with the Jynneos smallpox vaccine, which can also be effective after a person is infected, according to the Centers for Disease Control and Prevention.

Health officials noted that the efficacy data on the vaccine is not surprising because a study from the 1980s found that the shots could provide about 85% protection against monkeypox.

"What we're seeing are breakthrough cases, which are not really surprises, but it reminds us that vaccine is not a silver bullet, that every person who feels that they are a risk, and appreciates their own level of risk, and wishes to lower their own level of risk have many interventions at their disposal, which includes vaccination where available but also protection from activities where they may be at risk," Lewis said.

Monkeypox spreads primarily through skin-to-skin contact, direct contact with bodily fluids or lesions, and can also be transmitted by respiratory droplets. While the respiratory transmission may sound similar to COVID-19, monkeypox does not spread nearly as easily as the coronavirus.

The CDC states that individuals can protect themselves from the virus by avoiding skin-to-skin contact with people who have a rash that looks like monkeypox, avoiding contact with objects and materials that a person with monkeypox has used, and washing hands often.

As of Friday, there are 41,358 confirmed global cases of monkeypox across 94 countries, according to the Centers for Disease Control and Prevention. The United States counts more infections from the virus than any other country in the world with 14,115.

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