Vaccine News

A new report describes recent global polio outbreaks using data from the World Health Organization's Polio Information System and the Global Polio Laboratory Network.

On October 17, 2024, the U.S. CDC stated (MMWR 73(41);909–916) that circulating vaccine-derived polioviruses (cVDPVs) can emerge and cause outbreaks of paralytic polio in communities where there is a high percentage of undervaccinated children.

From January 2023–June 2024, 74 cVDPV outbreaks were detected in 39 countries or areas.

These poliovirus outbreaks caused 672 confirmed polio cases.

Among these 74 cVDPV outbreaks, 47 (64%) were new outbreaks detected in 30 of the 39 countries.

Since 2021, novel oral poliovirus vaccine type 2 (nOPV2), a more genetically stable vaccine with reduced risk for reversion to neurovirulence than Sabin-strain OPV2, has been the recommended vaccine for cVDPV2 outbreak response.

Since then, over 1 billion doses have been administered.

During January 2023–June 2024, cVDPV2 outbreaks were linked to nOPV2 use in 19 countries. These findings highlight that cVDPVs can develop with nOPV2 use when the timing and quality of vaccination responses are suboptimal.

This means prolonged community circulation of the vaccine strain leads to reversion to neurovirulence, seeding new emergences.

The CDC says that despite a slight decline in reported cVDPV2 cases compared with those reported during 2022, the number of countries or areas reporting outbreaks remained high. Stopping all cVDPV transmission requires effectively increasing population immunity by overcoming barriers to reaching children.

The CDC says the IPV, offered in the U.S. since 2000, can reduce the amount of poliovirus people shed but can't stop all virus transmission. 

The CDC recommends that international travelers speak with a healthcare provider about vaccine booster doses when visiting poliovirus-endemic countries in 2024.

A U.S. National Institutes of Health (NIH)-funded phase 2 clinical trial of a mpox vaccine in 229 adolescents found it was safe and well tolerated through study day 210, according to a planned interim analysis of study data.

As of October 16, 2024, the NIH also stated the analysis showed that the Bavarian Nordic A/S MVA-BN (JYNNEOS®) vaccine generated antibody levels in adolescents equivalent to those observed in adults at day 43.

According to the study team, the interim data support the safety and quality of the immune response generated by the MVA-BN vaccine in adolescents, findings relevant to the United States and other areas where mpox clade 2 cases have occurred.

The authors underscored the need to evaluate the MVA-BN vaccine in younger children to extend the evidence base to everyone affected by mpox clade 2.

The ongoing mpox clade 1 outbreak in Africa is evaluating the effectiveness of MVA-BN. 

In the U.S., the JYNNEOS vaccine is commercially available at various pharmacies. Additionally, three other mpox vaccines are being offered internationally in 2024.

The U.S. Centers for Disease Control and Prevention (CDC) recently issued interim recommendations to prevent the transmission of the Oropouche virus.

Oropouche is usually spread to people by the bite of an infected biting midge. Biting midges are tiny flies, often called "no-see-ums."

A recent scientific report describes Oropouche virus was found in the semen of a patient, which raises health concerns about the possible risk of sexual transmission.

A previous study described the shedding of Oropouche virus RNA in a symptomatic traveler's whole blood, serum, and urine. Virus replication was detected in semen 16 days after infection, which the authors say suggests a risk of sexual transmission. 

In June 2024, vertical transmission of the Oropouche virus was identified when RNA was detected in a stillborn infant born to a pregnant woman who had symptoms of Oropouche virus disease at 30 weeks gestation.

Therefore, as of October 15, 2024, the CDC announced men diagnosed with Oropouche infections are advised to use condoms or abstain from sex for six weeks starting from the onset of symptoms.

This is essential guidance since travel-related Oropouche cases have been confirmed in five states, including Florida (86).

Since there are no vaccines to prevent or medicines to treat Oropouche, the CDC says the best way to protect yourself from Oropouche is to prevent bites from biting midges and mosquitoes in areas where the virus is known to occur.

As of 2024, several countries in South America, Central America, and the Caribbean (Cuba) are reporting increased cases. In July 2024, the Brazil Ministry of Health reported two deaths, which represent the first reported fatalities attributed to the Oropouche virus disease in the Americas.

However, there is no evidence of Oropouche virus transmission within the U.S.

CSL Seqirus today announced new data from several studies that reinforce the benefits of cell-based influenza vaccines among people.

On October 16, 2024, Seqirus stated results from multiple real-world evidence studies over different seasons showed improved relative vaccine effectiveness of cell-based vaccines compared with egg-based vaccines in preventing outpatient test-confirmed influenza across various age groups.

“The results from these studies, collected and analyzed over several recent influenza seasons, have shown that cell-based influenza vaccines are effective in preventing both test-confirmed and clinically diagnosed influenza,” stated Mendel Haag, Senior Director, Center of Outcomes Research & Epidemiology at CSL Seqirus, in a press release.

As of October 2024, the U.S. CDC recommends that people speak with a healthcare provider, such as a pharmacist, about which of nine different flu shots is best for their needs.

The CDC says flu vaccines for the 2024-2025 season will be trivalent. Most will be thimerosal-free or thimerosal-reduced vaccine, and about 21% will be egg-free.

As of September 21, 2024, over 92 million flu shots had been distributed to clinics and pharmacies in the U.S., targeting the 2024-2025 flu season.

In Europe, the mosquito vector Aedes albopictus, established in many parts of Europe for years, transmits both chikungunya and dengue viruses.

Recently, France's Public Health Ministry stated that detecting additional dengue and chikungunya cases in 2024 has prompted epidemiological and entomological investigations.

As reported on October 9, 2024, the majority of locally-acquired and travel-related cases have been detected in southern France.

From January to April 30, 2024, 2,271 travel-related dengue fever cases and six imported chikungunya cases were reported.

From May 2024 to October 8, 2024, 1,634 imported cases of dengue fever, including 1,468 in departments where the establishment of Aedes albopictus has been documented, and 16 imported cases of chikungunya.

Overall, France reported 78 locally acquired dengue cases in 2024. In 2023, France reported nine outbreaks of dengue involving 45 cases of autochthonous human dengue virus infections.

In the past, local dengue outbreaks have been reported in Italy, Spain, and Croatia.

As of October 15, 2024, the U.S. CDC says chikungunya and dengue are a year-round risk in many parts of the world, and international travelers should take action to prevent infections. The CDC has identified more than expected mosquito-transmitted cases among U.S. travelers returning from various countries.

The Islamic Republic of Pakistan is one of two countries left in the world where poliovirus continues to threaten the health and well-being of its 250 million residents.

According to the weekly report published by the Global Polio Eradication Initiative (GPEI), Pakistan confirmed four new wild poliovirus type 1 (WPV1) cases. WPV1 is the only circulating wild poliovirus serotype.

The latest instances of paralysis were in Balochistan, Khyber Pakhtunkhwa, and Sindh provinces.

Furthermore, 50 WPV1-positive environmental samples were recently confirmed from Balochistan, Islamabad, Khyber Pakhtunkhwa, Punjab and Sindh.

As of October 14, 2024, Pakistan has reported 28 cases of WPV1 this year.

Since 1994, the Pakistan Polio Eradication Program has been fighting to end poliovirus infections. Through its efforts, case numbers in Pakistan have declined by up to 99% from the 20,000 cases reported in the early 1990s.

Unfortunately, the WHO reconfirmed in August 2024 that the spread of the poliovirus remained a Public Health Emergency of International Concern.

The U.S. CDC reported in September 2024 that routine immunization coverage with oral polio vaccines (OPV) and inactivated polio vaccine (IPV) in Pakistan has improved in recent years, as IPV protects against paralysis.

However, because it is an inactivated vaccine that does not replicate in the intestinal tract, as does OPV, it does not prevent the spread of poliovirus.

This could partly explain the relatively low number of WPV1 cases reported in the context of widespread WPV1 circulation as evidenced by environmental surveillance.

However, one-half of all WPV1 patients had never received OPV through routine immunization, indicating population immunity gaps. Whenever feasible, vaccination activities need to be synchronized with those of neighboring Afghanistan, says the CDC.

In Africa and Asia, the nOPV2 vaccine has been offered in 2024.

In the United States, the IPV has been offered since 2000, and booster doses are recommended for certain international travelers in 2024.

In early October 2024, the Republic of Rwanda began vaccinating frontline health workers in a Phase 2 rapid response open-label clinical trial to combat the reaction to the ongoing Marburg virus disease (MVD) outbreak, which has already claimed 14 lives.

Sabin Vaccine Institute’s single-dose Marburg vaccine candidate was selected to be administered in accordance with the clinical protocol reviewed and approved by Rwandan ethics and regulatory authorities. However, this is not a U.S. FDA-approved vaccine.

As of October 12, 2024, Sabin announced it had delivered approximately 1,700 investigational vaccine doses to Rwanda. 

“In an outbreak, every moment counts, and our seamless collaboration with the Rwandan government was key to accelerating the process. On our side, we moved quickly by leveraging our experience with other outbreaks and having vaccine doses and supporting documents ready, thanks to a strong partnership with ReiThera,” says Sabin's CEO Amy Finan in a press release.

Sabin has extensive expertise in advancing vaccines for filoviruses, with two programs currently in Phase 2 clinical trials—one for Marburg and the other for Sudan ebolavirus.

The U.S. government has obligated $235 million to Sabin to advance vaccine research and development against Sudan ebolavirus and MVD.

As of October 13, 2024, other MVD vaccine candidates are conducting clinical research.

Previously, the U.S. CDC announced that people should reconsider nonessential travel to the Republic of Rwanda and that those who arrive in the U.S. may be screened for the virus at certain airports.