Chanjo ya Mpox

Vikundi vyenye hatari kubwa:

• Wahudumu wa afya wanaoshughulikia wagonjwa wa mpox

• Watu walio na mguso wa karibu na wagonjwa waliothibitishwa (PEP — ndani ya siku 4-14)

• Wanaume wanaofanya ngono na wanaume (MSM) — katika muktadha wa mlipuko wa Clade II

• Wafanyakazi wa maabara wanaoshughulikia orthopoxvirus

Katika Afrika Mashariki (Clade Ib):

• Wahudumu wa afya katika maeneo ya milipuko

• Watu walio na mguso wa moja kwa moja na wagonjwa

• Watoto — Clade I inaathiri watoto pia

Wasafiri:

• Wasafiri wanaokwenda maeneo yenye milipuko hai ya mpox (DRC, nchi jirani)

• WHO haipendekezi chanjo kwa wasafiri wote — tu wale wenye hatari kubwa

Jynneos/MVA-BN:

• Mzio mkubwa kwa kiungo chochote (pamoja na protini za kuku, gentamicin, ciprofloxacin)

Si kizuizi (faida ya MVA-BN):

• VVU/UKIMWI — MVA-BN ni chanjo isiyojirudia, salama kwa watu wenye upungufu wa kinga

• Ujauzito — data finyu lakini MVA-BN haina uwezo wa kujirudia — tathmini hatari/faida

• Eczema/atopic dermatitis — MVA-BN ni salama (tofauti na ACAM2000 ambayo ni kizuizi)

Athari za kawaida:

• Maumivu kwenye sehemu ya sindano — 75-85%

• Uwekundu na uvimbe — 40-60%

• Ugumu kwenye sehemu ya sindano — 30-50%

• Uchovu — 25-35%

• Maumivu ya kichwa — 15-25%

• Maumivu ya misuli — 15-25%

• Homa nyepesi — 5-10%

Athari za kawaida kwa njia ya intradermal:

• Athari za eneo ni za kawaida zaidi na za muda mrefu zaidi kuliko njia ya intramuscular

• Rangi nyeusi ya ngozi kwenye sehemu ya sindano — inaweza kudumu wiki kadhaa

Athari nadra:

• Myocarditis — nadra sana (MVA-BN ina hatari ndogo zaidi kuliko ACAM2000)

• Anafylaksia — nadra sana

Ratiba ya kawaida (intramuscular):

• Dozi 2 za 0.5 ml kwa sindano ya misuli (IM): siku ya 0 na siku ya 28

Ratiba ya kipimo kidogo (intradermal):

• Dozi 2 za 0.1 ml kwa sindano ya intradermal: siku ya 0 na siku ya 28

• Inaruhusu chanjo mara 5 zaidi kwa kila vial — muhimu wakati wa uhaba

PEP (baada ya mguso):

• Dozi 1 ndani ya siku 4 — kinga bora

• Dozi ya 2 siku ya 28 ikiwa hatari inaendelea

Upatikanaji:

• Haipatikani kwa urahisi katika kliniki za kawaida za Afrika Mashariki

• Inapatikana kupitia programu za WHO/Africa CDC wakati wa milipuko

• Bei: ~USD 100-200 kwa dozi katika masoko ya Magharibi

Ufanisi dhidi ya mpox:

• Ufanisi wa ~76% baada ya dozi 1 na ~85% baada ya dozi 2 (data ya mazingira halisi kutoka mlipuko wa 2022)

• Kinga ya kliniki katika majaribio ya awali: ~95% (ndui ya kale, extrapolation)

Ufanisi wa PEP:

• Chanjo ndani ya siku 4 baada ya mguso: ufanisi wa ~78% katika kuzuia ugonjwa

Data kutoka milipuko ya 2022 (Clade II):

• Watu waliopewa dozi 2: kupungua kwa 86% kwa hatari ya mpox ikilinganishwa na wasio na chanjo

• Njia ya intradermal: ufanisi sawa na intramuscular

Changamoto ya Clade I:

• Data ya ufanisi dhidi ya Clade I (hatari zaidi) ni finyu

• Tafiti zinaendelea katika DRC na nchi za Afrika Mashariki

• Clade I ina kiwango cha vifo cha 5-10% (dhidi ya <0.1% kwa Clade II) — chanjo ni muhimu zaidi

Chanjo nyingine:

• Data ni finyu — WHO inapendekeza kutenganisha na chanjo nyingine kwa ≥wiki 4 ikiwa inawezekana

• Katika hali za dharura: inaweza kutolewa bila kuzingatia muda wa chanjo nyingine

Dawa:

• Dawa za kupunguza kinga: MVA-BN ni salama (isiyojirudia) lakini mwitikio wa kinga unaweza kupungua

• Tecovirimat (TPOXX — dawa ya mpox): hakuna data ya mwingiliano na chanjo

Pregnancy: JYNNEOS® (MVA-BN, non-replicating live vaccinia) has limited data in pregnant women. Animal studies showed no evidence of teratogenicity. During the 2022 mpox outbreak, the CDC recommended offering JYNNEOS® to pregnant persons with known mpox exposure, as mpox during pregnancy is associated with miscarriage, stillbirth, preterm delivery, and congenital mpox. The non-replicating nature of MVA-BN reduces theoretical risk compared to replication-competent smallpox vaccines. Individual risk–benefit assessment is recommended.

Breastfeeding: JYNNEOS® (MVA-BN, non-replicating live vaccinia) has limited data in lactating women. As a non-replicating vaccine, the risk of vaccine virus transmission through breast milk is theoretically lower than with replication-competent smallpox vaccines. During mpox outbreaks, vaccination may be considered for breastfeeding women with exposure, weighing the risk of mpox disease against the uncertain risk to the infant. Consult with a healthcare provider for individual risk assessment.

Pediatric use: JYNNEOS® is approved for adults ≥18 years in the US, though it has been used off-label in children during mpox outbreaks under emergency use authorization. In pediatric use during outbreaks, dosing follows adult dosing (0.5 mL subcutaneous, 2 doses 28 days apart). Children may be at risk of mpox through household contact with infected persons. ACAM2000® (replication-competent smallpox vaccine) has significant pediatric risks including progressive vaccinia and myocarditis and should only be used in children during emergencies.

Older adults (≥65 years): JYNNEOS® can be administered to older adults at risk of mpox exposure. Adults who received childhood smallpox vaccination (routine vaccination ended in the 1970s–1980s) may have residual cross-protective immunity against mpox, though this wanes over decades. JYNNEOS® is recommended regardless of prior smallpox vaccination for individuals at current risk. Older adults may experience more pronounced local and systemic reactions. No dose adjustment is required.

Mbinu ya kipimo kidogo (intradermal):

• WHO inapendekeza kipimo cha 1/5 (0.1 ml intradermal) badala ya 0.5 ml intramuscular wakati wa uhaba wa chanjo

• Ufanisi wa kinga unafanana — imetumiwa kwa mafanikio katika mlipuko wa 2022

• Njia ya intradermal inahitaji mafunzo maalum

Changamoto za Afrika Mashariki:

• Upatikanaji mdogo wa chanjo — Africa CDC na WHO zinafanya kazi kupata dozi

• Japan na EU zimetoa dozi za msaada kwa nchi za Afrika zinazoathiriwa

• Uzalishaji wa chanjo katika Afrika: BioVac (Afrika Kusini) inajaribu kuzalisha MVA-BN kwa leseni

PEP (post-exposure):

• Chanjo inapaswa kutolewa ndani ya siku 4 baada ya mguso kwa kinga bora

• Bado inafaidisha hadi siku 14 baada ya mguso