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The Centers for Disease Control and Prevention (CDC) began sounding the alarm about a potential rise in mpox (formerly monkeypox) outbreaks this summer, just days before publishing studies suggesting that two doses of Bavarian Nordic’s Jynneos vaccine, rather than one, offer “real-world” protection.

The World Health Organization (WHO) on May 11 ended the global health emergency for mpox — less than a week after it ended the COVID-19 emergency.

But on May 15, the CDC issued a health alert, warning that although mpox cases had declined since peaking last August, “the outbreak is not over.”

The alert informed clinicians and public health agencies that the CDC and local partners were investigating a cluster of mpox cases in the Chicago area, where 12 confirmed and one probable case of mpox had been reported to the Chicago Department of Public Health between April 17 and May 5.

Health officials should be aware of “the potential for new clusters or outbreaks of mpox cases,” the health alert warned. The CDC also warned that it was likely that “spring and summer season in 2023 could lead to a resurgence of mpox as people gather for festivals and other events.”

Nine of the possibly 13 infected men near Chicago were fully vaccinated against mpox, raising concerns over Jynneos’ efficacy. However, the CDC emphasized that “vaccination continues to be one of the most important prevention measures.”

The CDC’s announcement and the Chicago cases were widely covered in the press, leading cities like San Francisco to issue public health announcements encouraging vaccination.

On Thursday, just three days after the CDC issued its alert, the agency also published three new observational studies reporting that the Jynneos vaccine provides “real-world protection” against mpox, and two doses seem to be more effective than one.

Two of the studies were published in the CDC’s Morbidity and Mortality Weekly Report (MMWR) and one was published in the New England Journal of Medicine.

In one of the MMWR studies, a real-world case-match study conducted in 12 U.S. jurisdictions, two doses of Jynneos was estimated to be 85.9% effective against mpox. At one dose, the vaccine was found to be 75.2% effective.

But the CDC real-world study conducted in a larger pool of individuals published in the New England Journal of Medicine, showed much lower efficacy of Jynneos.

In that case-control analysis, in more than 10,000 people from a nationwide electronic health record database, Jynneos was estimated to be 66% effective after two doses, whereas the one-dose efficacy was just 35.8%.

According to Dr. Christopher Braden, the CDC’s mpox response incident manager, “Vaccine effectiveness estimates from these studies ranged from 36% to 75% for one dose and 66% to 86% for two doses of Jynneos vaccine.”

“What we take away from these three studies is that the vaccine effectiveness is substantial and that two doses is definitely better than one,” Braden added.

One of the MMWR reports also stated that “information on Jynneos vaccine effectiveness is limited.”

And Dr. Meryl Nass, a member of the Children’s Health Defense scientific advisory committee, also told The Defender that clinical trials were lacking to show effectiveness of the vaccine.

Nass reported on her Substack that the CDC began a study of monkeypox vaccine effectiveness in the Democratic Republic of Congo, but never reported the results.

The New York Times also questioned the vaccine’s effectiveness:

“Many questions remain about the vaccine, which had not been widely used before last summer’s outbreak of mpox, formerly called monkeypox, largely among men who have sex with men.

“None of the new studies were randomized controlled trials, and some of the analyses were small.

“More work is needed to determine how well the vaccine works in immunocompromised people, how long protection lasts and whether that varies depending on how the shots are administered.”

What is mpox?

Mpox is a disease caused by a poxvirus. Symptoms of monkeypox infection are usually mild and include fever, rash and swollen lymph nodes, and occasionally intense headache, back pain, muscle aches, lack of energy and skin eruptions that can cause painful lesions, scabs or crusts.

The virus rarely requires hospitalization — and those who are hospitalized are typically hospitalized for pain control. It is very rarely fatal. According to the WHO, of the nearly 90,000 mpox cases reported worldwide in 2022-2023, there were only 140 deaths.

Monkeypox primarily is spread through skin-to-skin contact during sex and affects mostly gay and bisexual men, public health officials said, although the virus can affect anyone.

According to the CDC, about 98% of monkeypox patients who provided demographic information to clinics identified as men who have sex with men.

The CDC characterizes monkeypox as “generally a mild disease,” involving little more than rashes, fevers and chills that typically require “no specific treatment.”

History of the monkeypox ‘threat’

As The Defender reported in May 2022, the Nuclear Threat Initiative, in conjunction with the Munich Security Conference, in March 2021 held a “tabletop exercise on reducing high-consequence biological threats,” involving an “unusual strain of monkeypox virus that first emerged in the fictional nation of Brinia and spread globally over 18 months.”

The fictional start date of the monkeypox pandemic in this exercise was May 15, 2022. The first European case of monkeypox was identified on May 7, 2022, and several cases were reported after that.

These reports were leading up to the World Health Assembly — the WHO’s decision-making body — meeting, which was set for May 22, 2022. The World Health Assembly scheduled an emergency monkeypox meeting for May 20, Nass reported on her Substack.

In late July 2022, WHO head Tedros Adhanom Ghebreyesus “side-stepped” his own advisors to pronounce monkeypox a “public health emergency of international concern,” the WHO’s first such ruling since SARS-CoV-2.

In August 2022, the Biden administration followed suit, declaring monkeypox a public health emergency to raise awareness and allow for additional funding to fight the disease’s spread, according to U.S. Department of Health and Human Services Secretary Xavier Becerra.

The Jynneos smallpox vaccine had already been licensed for adults in September 2019 for smallpox and for the prevention of monkeypox.

During the monkeypox scare in the summer of 2022, there was a shortage of available doses of the vaccine.

In August 2022, the U.S. Food and Drug Administration issued an Emergency Use Authorization allowing healthcare providers to administer a smaller amount of the Jynneos vaccine to high-risk individuals through intradermal injection — meaning between layers of the skin rather than below the skin — instead of subcutaneously, or beneath the skin.

The change in injection method increased available doses fivefold — from 441,000 to more than 2.2 million — as intradermal injection uses only a fraction of the dose but provides the same protection.