Several healthcare stocks associated with mpox are seeing increased attention Thursday after the World Health Organization declared a public health emergency in response to an mpox outbreak in Africa.

What Happened: WHO Director-General Tedros Adhanom Ghebreyesus determined this week that the recent surge of mpox, previously known as monkeypox, across a growing number of countries in Africa constitutes a public health emergency of international concern under International Health Regulations.

“The emergence of a new clade of mpox, its rapid spread in eastern DRC, and the reporting of cases in several neighbouring countries are very worrying. On top of outbreaks of other mpox clades in DRC and other countries in Africa, it's clear that a coordinated international response is needed to stop these outbreaks and save lives,” the WHO Director-General said.

Several stocks surged on the news Wednesday including Emergent Biosolutions Inc ( EBS ) , which owns one of two vaccines that have been recommended by the Centers for Disease Control and Prevention (CDC): ACAM2000. Bavarian Nordic’s (OTC:BVNRY) JYNNEOS is the other CDC recommended vaccine for mpox.

See Also: WHO Declares Mpox Public Health Emergency: ‘Coordinated International Response Essential’ To Halt Outbreak

Shares of GeoVax Labs Inc ( GOVX ) and SIGA Technologies Inc ( SIGA ) also traded higher on Wednesday, but they are moving in different directions Thursday.

Geovax Labs ( GOVX ) is a clinical-stage biotechnology company engaged in developing immunotherapies and vaccines against cancers and infectious diseases. The company previously published information in peer-reviewed journals suggesting its vaccines help prevent mpox. GeoVax ( GOVX ) shares were up approximately 83% over the past week at the time of writing.

SIGA Technologies ( SIGA ) is a commercial-stage pharmaceutical company focused on the health security market. The company’s lead product is TPOXX (tecovirimat), an orally administered antiviral drug for the treatment of human smallpox disease. Mpox is in the same virus family as smallpox, but it causes milder symptoms.

SIGA Technologies ( SIGA ) shares soared on Wednesday, but the stock is giving back all of its gains on Thursday after the National Institute of Allergy and Infectious Diseases announced top-line results from a preliminary analysis of a trial testing TPOXX for mpox virus did not meet its primary endpoint.

Although the study did not meet statistical significance, SIGA ( SIGA ) said results suggest TPOXX provides clinical benefit compared to placebo in patients who are treated early and in patents with severe disease.

“We believe these data warrant further investigation and support our view that post exposure prophylaxis will be vital for treatment of severe cases of mpox and all cases of smallpox,” said Dennis Hruby, chief scientific officer of SIGA Technologies ( SIGA ).

SIGA ( SIGA ) noted that additional studies are being conducted by trial sponsors around the world. These clinical trials are expected to help the company gain a deeper understanding of the potential for TPOXX to benefit patients with mpox. 

Related Link: In NIH-Cosponsored Monkeypox Virus Study In Congo, SIGA Technologies’ Antiviral Tecovirimat Did Not Improve Lesion Resolution, Stock Tanks

EBS, BNVRY, GOVX, SIGA Price Action: At publication time, Emergent Biosolutions ( EBS ) shares were up 12.3% at $8.50, Bavarian Nordic ( BVNKF ) shares were down 9.77% at $12.28, Geovax ( GOVX ) shares were up 13.5% at $3.69 and SIGA ( SIGA ) shares were down 29.4% at $8.45, according to Benzinga Pro.