{"id":891,"date":"2020-06-12T14:18:38","date_gmt":"2020-06-12T14:18:38","guid":{"rendered":"https:\/\/uni.hi.is\/apalsson\/?p=891"},"modified":"2020-06-12T14:19:08","modified_gmt":"2020-06-12T14:19:08","slug":"ef-eg-mynda-onaemi-fyrir-einni-utgafu-af-covid-19-hef-eg-tha-nokkud-vorn-fyrir-ollum-stokkbreyttu-utgafunum","status":"publish","type":"post","link":"https:\/\/uni.hi.is\/apalsson\/IS\/2020\/06\/12\/ef-eg-mynda-onaemi-fyrir-einni-utgafu-af-covid-19-hef-eg-tha-nokkud-vorn-fyrir-ollum-stokkbreyttu-utgafunum\/","title":{"rendered":"Ef \u00e9g mynda \u00f3n\u00e6mi fyrir einni \u00fatg\u00e1fu af COVID-19 hef \u00e9g \u00fe\u00e1 nokku\u00f0 v\u00f6rn fyrir \u00f6llum st\u00f6kkbreyttu \u00fatg\u00e1funum?"},"content":{"rendered":"

Arnar P\u00e1lsson. \u201eEf \u00e9g mynda \u00f3n\u00e6mi fyrir einni \u00fatg\u00e1fu af COVID-19 hef \u00e9g \u00fe\u00e1 nokku\u00f0 v\u00f6rn fyrir \u00f6llum st\u00f6kkbreyttu \u00fatg\u00e1funum?<\/a>\u201c V\u00edsindavefurinn<\/i>, 30. apr\u00edl 2020. http:\/\/visindavefur.is\/svar.php?id=79322.<\/p>\n

Upprunaleg spurning Bjarna var \u00ed l\u00f6ngu m\u00e1li:<\/p>\n

Er hjar\u00f0\u00f3n\u00e6mi e\u00f0a b\u00f3lusetning \u00f3raunh\u00e6f v\u00f6rn vegna fj\u00f6lda st\u00f6kkbreytinga? Ef s\u00e1 sem myndar \u00f3n\u00e6mi fyrir einni \u00fatg\u00e1fu af veirunni sem veldur COVID-19 vantar \u00fe\u00e1 ekki enn v\u00f6rn fyrir 569 st\u00f6kkbreyttum \u00fatg\u00e1fum? Mi\u00f0a\u00f0 vi\u00f0 a\u00f0 \u00cdslensk erf\u00f0agreining hefur hinga\u00f0 til samkv\u00e6mt K\u00e1ra skilgreint 570 st\u00f6kkbreytt afbrig\u00f0i af SARS-CoV-2? \u00de\u00e1 v\u00edsa \u00e9g l\u00edka til \u00feess sem segir \u00ed \u00f6\u00f0ru svari \u00e1 V\u00edsindavefnum: \"Mikilv\u00e6gt er \u00fe\u00f3 a\u00f0 taka fram a\u00f0 \u00f3n\u00e6misminni sem myndast vegna einnar ger\u00f0ar k\u00f3r\u00f3nuveiru mun ekki verja okkur gegn s\u00fdkingu annarrar ger\u00f0ar k\u00f3r\u00f3nuveiru.\" Sj\u00e1 svar vi\u00f0 spurningunni: Er h\u00e6gt a\u00f0 smitast tvisvar af COVID-19?<\/a>.<\/p><\/blockquote>\n

Stutta svari\u00f0 vi\u00f0 spurningunni er einfaldlega \u00feetta: \u00d3l\u00edklegt er a\u00f0 st\u00f6kkbreytingar sem \u00feegar hafa or\u00f0i\u00f0 \u00e1 veirunni sem veldur COVID-19 valdi \u00fev\u00ed a\u00f0 \u00f3n\u00e6miskerfi \u00feeirra sem hafa smitast muni ekki eftir veirunni. V\u00edsindamenn telja a\u00f0 sl\u00edk \u00fer\u00f3un veirunnar taki \u00e1r.<\/p>\n

Hva\u00f0 er st\u00f6kkbreyting?<\/h3>\n

Or\u00f0i\u00f0 st\u00f6kkbreyting<\/a> hefur mismunandi merkingu \u00ed almennu m\u00e1li og erf\u00f0afr\u00e6\u00f0i<\/a>. \u00cd erf\u00f0afr\u00e6\u00f0i er hugtaki\u00f0 nota\u00f0 um alls konar erf\u00f0afr\u00e1vik, fr\u00e1 mj\u00f6g sm\u00e1v\u00e6gilegum til \u00feeirra sem valda breytingum \u00e1 svipger\u00f0. \u00cd almennu m\u00e1li t\u00e1knar st\u00f6kkbreyting veigamiklar breytingar \u00e1 eiginleikum einstaklinga, samanber hugmyndir um X-mennin. \u00dev\u00ed er e\u00f0lilegt a\u00f0 f\u00f3lk hafi \u00e1hyggjur \u00feegar tala\u00f0 er um 40 e\u00f0a 570 n\u00fdjar st\u00f6kkbreytingar \u00ed veirunni sem veldur COVID-19<\/a>. G\u00f3\u00f0u fr\u00e9ttirnar eru hins vegar \u00fe\u00e6r a\u00f0 st\u00f6kkbreytingar eru f\u00e6star sl\u00e6mar. Mikill meirihluti st\u00f6kkbreytinga sem finnast \u00ed f\u00f3lki hafa til d\u00e6mis engin \u00e1hrif \u00e1 h\u00e6fni einstaklinga. A\u00f0 sama skapi f\u00e6r hver einstaklingur milli 40 og 120 n\u00fdjar einsbasa breytingar fr\u00e1 foreldrum s\u00ednum. Engu a\u00f0 s\u00ed\u00f0ur eru n\u00e6r \u00f6ll b\u00f6rn mj\u00f6g l\u00edk foreldrum s\u00ednum, enda hafa f\u00e6star \u00feessara breytinga veruleg \u00e1hrif \u00e1 \u00fatlit e\u00f0a svipfar.<\/span>[1]<\/a><\/sup> En hva\u00f0 me\u00f0 \u00feessar st\u00f6kkbreytingar \u00ed veirunni sem veldur COVID-19? Kveikjan a\u00f0 spurningunni er n\u00fdleg fr\u00e9tt um a\u00f0 570 breytingar hef\u00f0u fundist \u00ed veirunum sem hef\u00f0u veri\u00f0 ra\u00f0greindar \u00far f\u00f3lki \u00e1 \u00cdslandi.<\/span>[2]<\/a><\/sup> \u00c1 heimsv\u00edsu hafa r\u00famlega \u00ferj\u00e1r millj\u00f3nir manna greinst smita\u00f0ir og 12.000 veiruerf\u00f0amengi veri\u00f0 ra\u00f0greind.<\/span>[3]<\/a><\/sup> Fj\u00f6ldi st\u00f6kkbreytinga sem or\u00f0i\u00f0 hafa \u00ed veirunni fr\u00e1 \u00fev\u00ed a\u00f0 faraldurinn h\u00f3fst er \u00fev\u00ed umtalsver\u00f0ur. \u00c1st\u00e6\u00f0an er s\u00fa a\u00f0 \u00ed hvert skipti sem veiran SARS-CoV-2 fj\u00f6lgar s\u00e9r og smitast fr\u00e1 einum einum einstaklingi til annars, ver\u00f0a breytingar \u00e1 erf\u00f0efni hennar.<\/p>\n

St\u00f6kkbreytingar hafa \u00e1hrif \u00e1 h\u00e6fni<\/h3>\n

H\u00e6gt er a\u00f0 l\u00edta \u00e1 st\u00f6kkbreytingar \u00ed erf\u00f0aefni \u00e1 tvo vegu. \u00cd fyrsta lagi me\u00f0 \u00fev\u00ed a\u00f0 meta \u00e1hrif st\u00f6kkbreytinganna \u00e1 h\u00e6fni l\u00edfverunnar. \u00cd \u00f6\u00f0ru lagi m\u00e1 sko\u00f0a hvar st\u00f6kkbreytingin ver\u00f0ur \u00ed erf\u00f0aefninu, og hva\u00f0a aflei\u00f0ingar h\u00fan hefur fyrir virkni gensins e\u00f0a eiginleika l\u00edfverunnar. \u00c1hrif st\u00f6kkbreytinga \u00e1 h\u00e6fni<\/span>[4]<\/a><\/sup> falla \u00ed \u00ferj\u00e1 flokka:<\/p>\n

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  1. Neikv\u00e6\u00f0ar breytingar, \u00fea\u00f0 er st\u00f6kkbreytingar sem geta dregi\u00f0 \u00far h\u00e6fni l\u00edfveru, me\u00f0 \u00fev\u00ed a\u00f0 sker\u00f0a fj\u00f6lgunargetu e\u00f0a l\u00edfsl\u00edkur.<\/li>\n
  2. J\u00e1kv\u00e6\u00f0ar, \u00fea\u00f0 er geta auki\u00f0 h\u00e6fni l\u00edfveru, me\u00f0 \u00fev\u00ed a\u00f0 breyta virkni henni \u00feannig a\u00f0 l\u00edfsl\u00edkur aukast e\u00f0a fj\u00f6lgunargeta eykst.<\/li>\n
  3. Hlutlausar st\u00f6kkbreytingar, \u00fea\u00f0 er hafa engin \u00e1hrif \u00e1 h\u00e6fni l\u00edfveru.<\/li>\n<\/ol>\n

    \u00de\u00e6r breytingar sem finnast \u00ed stofnum l\u00edfvera eru flestar af ger\u00f0 3, en j\u00e1kv\u00e6\u00f0ar breytingar eru sjaldg\u00e6far. Litlar l\u00edkur ver\u00f0a raunverulegar ef teningnum er kasta\u00f0 n\u00f3gu oft. Eins og \u00e1\u00f0ur hefur veri\u00f0 fjalla\u00f0 um \u00e1 V\u00edsindavefnum, eykst h\u00e6ttan \u00e1 a\u00f0 j\u00e1kv\u00e6\u00f0 breyting ver\u00f0i \u00ed erf\u00f0aefni veirunnar me\u00f0 auknum fj\u00f6lda smita.<\/span>[5]<\/a><\/sup> Ef a\u00f0eins 1.000 manns smitast \u00fe\u00fd\u00f0ir \u00fea\u00f0 1.000 m\u00f6guleika fyrir st\u00f6kkbreytingar me\u00f0 j\u00e1kv\u00e6\u00f0 \u00e1hrif \u00e1 h\u00e6fni veirunnar. Ef fimmt\u00edu millj\u00f3nir manna smitast aukast l\u00edkurnar \u00e1 breytingum sem eru veirunni \u00ed hag. Hver veirukynsl\u00f3\u00f0 skiptir m\u00e1li og \u00fev\u00ed er gr\u00ed\u00f0arlega mikilv\u00e6gt a\u00f0 koma h\u00f6mlum \u00e1 \u00fatbrei\u00f0slu veirunnar.<\/p>\n

    \u00c1hrif st\u00f6kkbreytinga \u00e1 pr\u00f3t\u00edn og virkni<\/h3>\n

    H\u00e6gt er a\u00f0 sp\u00e1 fyrir um hvort st\u00f6kkbreytingar s\u00e9u j\u00e1kv\u00e6\u00f0ar, neikv\u00e6\u00f0ar e\u00f0a hlutlausar me\u00f0 \u00fev\u00ed a\u00f0 sko\u00f0a \u00e1hrif \u00feeirra \u00e1 gen l\u00edfvera. Sl\u00edkar sp\u00e1r eru h\u00e1\u00f0ar \u00f3vissu, en gera okkur samt kleift a\u00f0 meta hvort tiltekin st\u00f6kkbreyting geti haft \u00e1hrif \u00e1 virkni gena og \u00fear me\u00f0 h\u00e6fni. \u00cd tilfelli veirunnar sem veldur COVID-19 getum vi\u00f0 athuga\u00f0 hvar st\u00f6kkbreytingar lenda \u00ed erf\u00f0amengi veirunnar og hvort genin raskist e\u00f0a ver\u00f0i ekki fyrir \u00e1hrifum. Erf\u00f0amengi veirunnar er a\u00f0 me\u00f0altali 29903 basap\u00f6r, og \u00fea\u00f0 skr\u00e1ir n\u00e6r allt fyrir pr\u00f3t\u00ednum. Tali\u00f0 er a\u00f0 \u00fea\u00f0 skr\u00e1i fyrir 29 \u00f3l\u00edkum pr\u00f3t\u00ednum, hlutverk sumra er \u00feekkt en annarra ekki.<\/span>[6]<\/a><\/sup> St\u00f6kkbreytingar \u00ed erf\u00f0efni veirunnar geta anna\u00f0 hvort valdi\u00f0 breytingu \u00e1 r\u00f6\u00f0 pr\u00f3t\u00edna e\u00f0a ekki. St\u00f3rt hlutfall st\u00f6kkbreytinga sem fundist hafa \u00ed veirunni breyta ekki byggingu pr\u00f3t\u00edna veirunnar. \u00deetta eru svokalla\u00f0ar \u00fe\u00f6glar breytingar. L\u00edklegast er a\u00f0 n\u00e6r allar s\u00e9u \u00fer\u00f3unarfr\u00e6\u00f0ilega hlutlausar. \u00de\u00e6r munu ekki gera veirunni kleift a\u00f0 sleppa fr\u00e1 \u00f3n\u00e6miskerfinu.<\/span>[7]<\/a><\/sup> M\u00f3tefni sem \u00f3n\u00e6miskerfi\u00f0 framlei\u00f0ir \u00f3virkjar veirur og s\u00fdkingar \u00e1 marga vegu. \u00deau bindast s\u00fdklum og st\u00fdra dr\u00e1pi \u00e1 s\u00fdktum frumum.<\/span>[8]<\/a><\/sup> B\u00fatar e\u00f0a hlutar pr\u00f3t\u00edna veirunnar mynda svokalla\u00f0a m\u00f3tefnav\u00edsa (e. epitope), sem \u00f3n\u00e6miskerfi\u00f0 skynjar. M\u00f3tefni gegn veirunni SARS-CoV-2 g\u00e6tu til d\u00e6mis bundist ytra byr\u00f0i agnarinnar og \u00feannig heft framvindu s\u00fdkingar. \u00d3n\u00e6misfrumur einstaklings muna eftir eldri s\u00fdklum og geta svara\u00f0 seinna smiti hratt og afgerandi. \u00dea\u00f0 er lykillinn \u00ed b\u00f3luefnum, a\u00f0 kenna \u00f3n\u00e6miskerfinu a\u00f0 \u00feekkja s\u00fdkla af \u00e1kve\u00f0num ger\u00f0um.<\/p>\n

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    Einf\u00f6ld sk\u00fdringarmynd af veirunni SARS-CoV-2. Bindipr\u00f3t\u00ednin eru \u00e1 ytra byr\u00f0i veirunnar. \u00deau tengjast vi\u00f0t\u00f6kum h\u00fdsilfrumunnar og \u00feannig kemst veiran inn \u00ed hana.<\/p>\n<\/div>\n<\/div>\n

    V\u00edkjum aftur a\u00f0 veirunni. Skipti \u00e1 am\u00edn\u00f3s\u00fdrum \u00ed \u00f6llum 29 pr\u00f3t\u00ednum veirunnar geta m\u00f6gulega gert henni kleift a\u00f0 v\u00edkja s\u00e9r undan minni \u00f3n\u00e6miskerfisins. En ekki eru \u00f6ll pr\u00f3t\u00edn j\u00f6fn. L\u00edklegra er a\u00f0 breytingar \u00e1 tilteknum pr\u00f3t\u00ednum veirunnar au\u00f0veldi henni a\u00f0 sleppa undan \u00f3n\u00e6miskerfinu. Sennilega er svokalla\u00f0 bindipr\u00f3t\u00edn mikilv\u00e6gast \u00ed \u00feessu samhengi. \u00dea\u00f0 stendur \u00fat \u00far yfirbor\u00f0i veiruagna og stu\u00f0lar a\u00f0 innlimun \u00feeirra \u00ed frumur. Eins og fjalla\u00f0 ver\u00f0ur um s\u00ed\u00f0ar, er einnig m\u00f6gulegt a\u00f0 \u00f6nnur pr\u00f3t\u00edn veirunnar veki m\u00f3tefnasvar. Mikilv\u00e6gi bindipr\u00f3t\u00ednsins er stutt ranns\u00f3knum \u00e1 \u00fer\u00f3un erf\u00f0amengja annarrar k\u00f3r\u00f3nuveira. Greining \u00e1 erf\u00f0amengjum og s\u00f6gu smita OC43-veirunnar<\/a> \u00ed heilan \u00e1ratug s\u00fdndi til d\u00e6mis a\u00f0 bindipr\u00f3t\u00edni\u00f0 \u00fer\u00f3ast hra\u00f0ast. \u00dear ur\u00f0u flestar breytingar \u00e1 byggingu pr\u00f3t\u00ednanna. \u00c1st\u00e6\u00f0an er s\u00fa a\u00f0 breytingar \u00e1 am\u00edn\u00f3s\u00fdrur\u00f6\u00f0 veirupr\u00f3t\u00edns geta valdi\u00f0 \u00fev\u00ed a\u00f0 \u00f3n\u00e6miskerfi einstaklings \u00feekki veiruna ekki aftur. L\u00edklega \u00fearf margar sl\u00edkar st\u00f6kkbreytingar til a\u00f0 sleppa fr\u00e1 minni \u00f3n\u00e6miskerfisins (\u00fea\u00f0 er a\u00f0 segja ein st\u00f6kkbreyting dugir ekki til).<\/p>\n

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    \u00der\u00f3unarsaga og mynstur basaskipta \u00ed erf\u00f0amengi OC43-veirunnar. Efri hlutinn s\u00fdnir \u00fer\u00f3unars\u00f6gu heilra\u00f0greindra veira fr\u00e1 1976 til 2019. Hver punktur t\u00e1knar greint s\u00fdni og \u00feau eru tengd \u00ed t\u00f6lfr\u00e6\u00f0ilega meti\u00f0 \u00e6ttartr\u00e9. Ne\u00f0ri hlutinn s\u00fdnir byggingu litnings veirunnar, s\u00falurnar t\u00e1kna basabreytingar. \u00dev\u00ed h\u00e6rri sem s\u00falan er, \u00fev\u00ed fleiri breytingar hafa or\u00f0i\u00f0 e\u00f0a meiri munur \u00e1 t\u00ed\u00f0ni ger\u00f0a yfir t\u00edmabili\u00f0. Bl\u00e1leitur kassi er utan um geni\u00f0 sem skr\u00e1ir fyrir bindipr\u00f3t\u00edninu sem er s\u00e9rstaklega breytilegt. Myndina ger\u00f0i Emma Hodcroft eftir g\u00f6gnum fr\u00e1 Ren o.fl. 2015.<\/p>\n<\/div>\n<\/div>\n

    Hr\u00f6\u00f0 \u00fer\u00f3un bindipr\u00f3t\u00ednsins er \u00fev\u00ed merki um a\u00f0 \u00fea\u00f0 hafi \u00fer\u00f3ast fr\u00e1 \u00f3n\u00e6miskerfinu. \u00deannig a\u00f0 einstaklingar sem smitu\u00f0ust af eldri ger\u00f0um \u00feeirrar veiru, b\u00fai ekki lengur yfir \u00f3n\u00e6mi. \u00deetta er raunverulegur m\u00f6guleiki sem vir\u00f0ist eiga s\u00e9r sta\u00f0 hj\u00e1 \u00f6\u00f0rum k\u00f3r\u00f3nuveirum sem s\u00fdkja menn og \u00fev\u00ed l\u00edklegt a\u00f0 svipu\u00f0 gerist hj\u00e1 \u00feessari n\u00fdju veiru. Benda \u00fearf \u00e1 tv\u00f6 atri\u00f0i til vi\u00f0b\u00f3tar. \u00der\u00f3un OC43-veirunnar s\u00fdnir a\u00f0 fleiri sv\u00e6\u00f0i \u00ed erf\u00f0amengi veirunnar hafa \u00fer\u00f3ast hratt. \u00dea\u00f0 g\u00e6ti l\u00edka tengst fl\u00f3tta hennar undan \u00f3n\u00e6miskerfum okkar. Einnig skiptir m\u00e1li a\u00f0 \u00fer\u00f3un OC43-veirunnar var\u00f0 yfir margra \u00e1ra e\u00f0a \u00e1ratuga langt t\u00edmabil. \u00dea\u00f0 bendir til a\u00f0 \u00fer\u00f3un k\u00f3r\u00f3nuveira fr\u00e1 \u00f3n\u00e6misminni taki umtalsver\u00f0an t\u00edma. \u00dea\u00f0 er a\u00f0 minnsta kosti \u00e1lyktun Trevors Bedford, s\u00e9rfr\u00e6\u00f0ings \u00ed \u00fer\u00f3un og stofnerf\u00f0af\u00e6\u00f0i veira vi\u00f0 h\u00e1sk\u00f3lann \u00ed Washington. Ranns\u00f3knarh\u00f3pur hans hefur kortlagt smit og dreifingu veirunnar \u00e1 heimsv\u00edsu \u00ed einst\u00f6ku verkefni sem nefnist Nextstrain<\/a>. Trevor l\u00fdsti \u00fev\u00ed n\u00fdlega yfir \u00e1 Twitter.com \u201ea\u00f0 \u00fea\u00f0 t\u00e6ki veiruna l\u00edklega nokkur \u00e1r a\u00f0 st\u00f6kkbreytast n\u00e6gilega miki\u00f0 til a\u00f0 gera b\u00f3lusetningu gagnslausa.\u201c<\/span>[9]<\/a><\/sup> \u00cd sama streng tekur Nick Loman, pr\u00f3fessor og s\u00e9rfr\u00e6\u00f0ingur \u00ed erf\u00f0amengjafr\u00e6\u00f0i og l\u00edfuppl\u00fdsingafr\u00e6\u00f0i \u00f6rvera vi\u00f0 h\u00e1sk\u00f3lann \u00ed Birmingham. \u00cd vi\u00f0tali vi\u00f0 Financial Times<\/cite> \u00e1lykta\u00f0i hann a\u00f0 \u201evi\u00f0 getum sannarlega b\u00faist vi\u00f0 a\u00f0 einhverjar st\u00f6kkbreytingar breyti eiginleikum veirunnar, en a\u00f0 ekki s\u00e9u v\u00edsbendingar um a\u00f0 \u00feetta hafi \u00feegar gerst\u201c.<\/span>[10]<\/a><\/sup> Me\u00f0 \u00f6\u00f0rum or\u00f0um, \u00f3l\u00edklegt er a\u00f0 st\u00f6kkbreytingar sem \u00feegar hafi or\u00f0i\u00f0 \u00e1 veirunni til \u00feessa (til d\u00e6mis \u00feessar 570 sem fundist hafa h\u00e9rlendis) valdi \u00fea\u00f0 miklum breytingum \u00e1 veirunni, a\u00f0 h\u00fan sleppi fr\u00e1 \u00f3n\u00e6mikerfi \u00feeirra sem lifa\u00f0 hafa s\u00fdkinguna af.<\/p>\n

    Samantekt<\/h3>\n