Just a small decline in childhood measles vaccination levels can produce disproportionate negative effects both to public health and the economy, new research has revealed.
Vaccines save lives. But in some regions across the US vaccination rates are declining due to bad information and poor choices, and now scientists have put together data on how badly these choices can affect us all.
A team from Stanford University and Baylor College of Medicine looked into the public health and economic impact of vaccine hesitancy, "defined as a delay or refusal to accept vaccination based on personal beliefs despite availability."
In other words, they ran the numbers on what even a handful of anti-vaxxers can cost the public, and those numbers ain't pretty.
Using the combined measles, mumps, and rubella (MMR) vaccine and the measles virus as a case example, the researchers built a computer model to estimate thousands scenarios of increased vaccine hesitancy, and how that would affect hypothetical measles outbreaks.
"We focussed on measles as a case example of the effects of declining vaccine coverage because it is highly infectious," says lead researcher Nathan Lo from Stanford University.
"It's likely to be the first infectious disease causing outbreaks if vaccination declines."
The team's data indicates that just a small 5 percent drop in MMR vaccine coverage of children aged 2-11 would result in a tripling of annual measles cases in this age group, from the current 48 cases per year to a whopping 150.
Now that may not sound like a lot of sick children, but measles is a rashy, insanely contagious illness that can cause serious or even fatal complications. It is still one of the leading global causes of death in children, mostly happening in developing parts of the world without adequate vaccine coverage.
Before we had a way to prevent measles through vaccination, millions of children died every year, a devastating number that has been steadily decreasing.
"During 2000-2015, measles vaccination prevented an estimated 20.3 million deaths," reports the World Health Organisation.
The reason overall vaccination levels are so important is because of the way vaccines prevent disease. There's always a small part of the population that can't be vaccinated for medical reasons (for example, kids with a compromised immune system), or are too young (babies can only get the first dose of MMR vaccine when they're one year old). All of them are super-vulnerable to rogue viruses.
These days in the US most measles cases occur when people have been travelling abroad and unwittingly bring the disease back. An infected person then becomes a disease vector, spreading it to anyone who isn't protected.
In an ideal situation, 90-95 percent of people would be vaccinated, and the virus is unable to take hold. Which makes that small group who is unable to be vaccinated entirely dependent on everyone around them, a principle called 'herd immunity'.
That's why it's so crucial that people don't opt out of vaccination - they are not just making a personal choice, but instead affecting their community as a whole. And because vaccine hesitant parents tend to live in clusters, it makes the potential of large outbreaks that much more likely.
Just this year, the Somali-American community in Minnesota experienced an outbreak of the deadly disease which surpassed all last year's US cases taken together.
And it's not just the public health argument alone. The Stanford-led team also ran some numbers on how much a drop in MMR vaccination coverage would cost in monetary terms.
At a conservative estimate, that same 5 percent drop in vaccination could cause an additional US$2.1 million expense for the public health sector. And the researchers note that this doesn't even include personal costs to families, loss of productivity to the parents, hospitalisation costs and other possible economic impacts.
"I think our study is a wake-up call for what we can expect in the coming months and years as vaccine coverage rates continue to decline in the 18 states that now allow non-medical or philosophical belief exemptions," says senior researcher Peter Hotez from Baylor College of Medicine.
The team hopes that their findings are going to play a role in policy making across the US.
"These findings should play a key role in any policies adopted by state or national governments that relate to childhood vaccination," they write in the study.
The research is available open-access in JAMA Pediatrics.
Kupungua kwa kiwango cha chanjo ya surua kwa watoto kunaweza kusababisha athari mbaya kwa afya ya umma na uchumi, utafiti mpya umefunua. Chanjo huokoa uhai. Katika baadhi ya maeneo ya Marekani, viwango vya chanjo vinapungua kwa sababu ya habari mbaya na uchaguzi mbaya, na sasa wanasayansi wamekusanya data juu ya jinsi uchaguzi huu unaweza kutufanya sisi sote. Timu ya wataalamu kutoka Chuo Kikuu cha Stanford na Chuo Kikuu cha Tiba cha Baylor ilichunguza athari za afya ya umma na kiuchumi za kukataa chanjo, "kufafanuliwa kama kuchelewesha au kukataa kukubali chanjo kulingana na imani za kibinafsi licha ya upatikanaji." Kwa maneno mengine, walifanya hesabu juu ya kile hata wachache wa wapinga-vaxxers wanaweza kugharimu umma, na idadi hizo sio nzuri. Kwa kutumia chanjo ya mchanganyiko ya homa, mumps, na rubella (MMR) na virusi vya homa kama mfano wa kesi, watafiti walijenga mfano wa kompyuta kukadiria maelfu ya matukio ya kuongezeka kwa wasiwasi wa chanjo, na jinsi hiyo itaathiri milipuko ya homa ya hedhi. "Tuliangalia ugonjwa wa surua kama mfano wa athari za kupungua kwa chanjo kwa sababu ni ya kuambukiza sana, ""anasema mtafiti mkuu Nathan Lo kutoka Chuo Kikuu cha Stanford." "Inawezekana kuwa ugonjwa wa kwanza wa kuambukiza kusababisha milipuko ikiwa chanjo itapungua". Takwimu za timu hiyo zinaonyesha kuwa kupungua kwa asilimia tano tu katika chanjo ya MMR kwa watoto wenye umri wa miaka miwili hadi kumi na moja kungesababisha kuongezeka kwa mara tatu kwa visa vya ugonjwa wa surua katika kikundi hiki cha umri, kutoka kesi 48 za sasa kwa mwaka hadi 150 kubwa. Huenda hilo lisisikike kama watoto wengi wagonjwa, lakini surua ni ugonjwa wa kuambukiza ambao unaweza kusababisha matatizo makubwa au hata ya kifo. Ugonjwa huu bado ni moja ya sababu kuu za vifo vya watoto duniani kote, hasa katika maeneo ya maendeleo ya dunia ambayo hayana chanjo ya kutosha. Kabla ya kupata njia ya kuzuia homa kwa kutumia chanjo, mamilioni ya watoto walikufa kila mwaka, idadi kubwa ambayo imekuwa ikipungua. "Katika kipindi cha mwaka wa 2000 hadi 2015, chanjo ya ugonjwa wa surua ilizuia vifo vya takriban watu milioni 20.3,"" inasema shirika la afya duniani WHO." Sababu ya viwango vya jumla vya chanjo kuwa muhimu sana ni kwa sababu ya njia chanjo zinazozuia ugonjwa. Kuna sehemu ndogo ya watu ambao hawawezi kupigwa chanjo kwa sababu za matibabu (kwa mfano, watoto wenye mfumo wa kinga ulioharibiwa) au ni wadogo sana (watoto wanaweza tu kupata kipimo cha kwanza cha chanjo ya MMR wanapokuwa na umri wa mwaka mmoja). Yote hayo ni hatari sana kwa virusi vya ujanja. Katika nchi za Ulaya, watu wengi wanaugua ugonjwa wa surua baada ya kusafiri nje ya nchi na kuingiza ugonjwa huo. Mtu aliyeambukizwa kisha anakuwa vector ya ugonjwa, kueneza kwa mtu yeyote ambaye si kulindwa. Katika hali nzuri, asilimia 90-95 ya watu watapewa chanjo, na virusi havitaweza kuenea. "Hii inamaanisha kwamba kikundi kidogo ambacho hakijaweza kupatiwa chanjo kinategemea kabisa kila mtu aliye karibu nao, kanuni inayoitwa ""kinga ya kundi.""" "Hii ndiyo sababu ni muhimu sana kwamba watu wasijaribu kujiondoa kwenye chanjo - sio tu wanafanya chaguo la kibinafsi, lakini badala yake wanaathiri jamii yao kwa ujumla. """ Kwa sababu wazazi wanaokataa chanjo wana mwelekeo wa kuishi katika makundi, inawezekana zaidi kutokea kwa milipuko mikubwa. Jamii ya Wasomali wa Marekani huko Minnesota ilipata janga la ugonjwa huo wa kuua ambao ulizidi visa vyote vya mwaka jana nchini Marekani pamoja. Na si hoja ya afya ya umma tu. Timu ya Stanford pia ilifanya hesabu juu ya jinsi kupungua kwa chanjo ya MMR ingegharimu kwa maneno ya fedha. Kwa makadirio ya kihafidhina, kupungua kwa asilimia 5 katika chanjo hiyo inaweza kusababisha gharama ya ziada ya dola milioni 2.1 kwa sekta ya afya ya umma. "Wanasayansi wanasema kuwa ""hiyo haijumuishi gharama za kibinafsi kwa familia, hasara ya uzalishaji kwa wazazi, gharama za kulazwa hospitalini na athari nyingine za kiuchumi.""" "Nafikiri utafiti wetu ni wito wa kuamsha kwa kile tunaweza kutarajia katika miezi na miaka ijayo kama viwango vya chanjo vinaendelea kupungua katika majimbo 18 ambayo sasa huruhusu msamaha wa imani isiyo ya matibabu au ya kifalsafa, ""anasema mtafiti mwandamizi Peter Hotez kutoka Chuo cha Tiba cha Baylor." Timu hiyo inatarajia kwamba matokeo yao yatakuwa na athari kubwa katika kutengeneza sera za afya nchini Marekani. "Ugunduzi huu unapaswa kuwa na jukumu muhimu katika sera zozote zinazopitishwa na serikali za jimbo au za kitaifa zinazohusiana na chanjo ya utotoni", wanaandika katika utafiti huo. Utafiti huo unapatikana kwa upatikanaji wazi katika JAMA Pediatrics.