Top post on /r/Iceland **https://www.reddit.com/r/Iceland/comments/oye5mu/b%C3%B3luefni_og_virkni_%C3%BEeirra_%C3%BEa%C3%B0_sem_gleymist/** Bóluefni og virkni þeirra. Það sem gleymist. Hamfarir Margir aðilar hafa lýst vonbrigðum með virkni bóluefna í því að verja einstakling gegn smiti. Til dæmis var Pfizer bóluefnið sagt hafa í kringum 93% virkni, en virkni bóluefnisins virðist mun minni ef miðað er við smittölur á Íslandi. Málið er að niðurstöður bóluefnaframleiðanda miða við smit + einkenni. Þ.e.a.s. ef sjúklingur í prófunarhópi Pfizer fékk jákvætt úr smitgreiningu en sýndi engin einkenni þá taldist bóluefnið virka. Íslendingar aftur á móti telja öll smit með, líka þau þar sem sjúklingur hefur engin einkenni. Stór hluti smitaðra á Íslandi hefur engin einkenni en er með jákvætt úr PCR prófi. Bóluefnaframleiðandi myndi telja að bóluefnið hafi varið viðkomandi en Landlæknir að bóluefnið hafi ekki virkað. Ég hef engar athugasemdir um það hvor skilgreiningin sé rétt en ég vildi benda á þetta því þessi munur hefur ekkert komið fram í fjölmiðlum eða frá farsóttaryfirvöldum. Þessi munur á skilgreiningu útskýrir "vonbrigðin" með virkni bóluefnanna. Heimildir: https://www.washingtonpost.com/health/2020/11/09/pfizer-coronavirus-vaccine-effective/ https://www.mbl.is/frettir/innlent/2021/07/23/97_prosent_einkennalitil_eda_naer_einkennalaus/ https://www.visir.is/g/20212133722d **Translated to English:** Vaccines and their efficacy. What is forgotten. Disaster Many people have expressed disappointment with the effectiveness of vaccines in protecting a person against infection. For example, the Pfizer vaccine was said to have around 93% activity, but the effectiveness of the vaccine seems to be much lower compared to infection rates in Iceland. The point is that the vaccine manufacturer's results are based on infection + symptoms. Ie. if a patient in the Pfizer test group tested positive for infection but showed no symptoms then the vaccine was considered effective. Icelanders, on the other hand, include all infections, including those where the patient has no symptoms. A large proportion of those infected in Iceland have no symptoms but have a positive PCR test. The vaccine manufacturer would believe that the vaccine had protected the person in question, but the Medical Director of Health that the vaccine had not worked. I have no comment on which definition is correct, but I would like to point this out because this difference has not been reported in the media or by the epidemic authorities. This difference in definition explains the "disappointment" with the effectiveness of the vaccines. Sources: https://www.washingtonpost.com/health/2020/11/09/pfizer-coronavirus-vaccine-effective/ https://www.mbl.is/frettir/innlent/2021/07/23/97_prosent_einkennalitil_eda_naer_einkennalaus/ https://www.visir.is/g/20212133722d