The CDC's weekly report carried five cases of Pneumocystis pneumonia in previously healthy young men in Los Angeles, two of them already dead. It is the first published account of what became AIDS, four years before the virus behind it was agreed on.
The report ran in the Morbidity and Mortality Weekly Report of 5 June 1981, filed among the ordinary notifiable-disease notes. [S]
Pneumocystis pneumonia in a healthy adult was the signal: the infection only takes hold when immunity has collapsed. [S]
HIV has killed more than 40 million people since; antiretroviral treatment now makes it a manageable lifelong infection and stops transmission.
The first entry is always the pin's source. Overall confidence is a weighted average of how firmly each reference supports the start and end times used above; a reference counts half as much for every 180 days older than the newest.
en.wikipedia.org· Added Sep 21, 2026· 50% of score
What the five cases turned out to be, and the four decades of epidemic that followed.[1]
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ESTIMATED68% CONFIDENCE108.6 years ago4 March 1918 is the first recorded case at Camp Funston, which is the earliest documented outbreak rather than a proven origin - the pandemic's beginning is genuinely disputed.[1]
A camp cook reported sick at Fort Riley's Camp Funston in Kansas, and within days hundreds of soldiers were down with influenza. It is the first recorded outbreak of the pandemic that killed more people than the war it travelled with - somewhere between 25 and 50 million.
ESTIMATED50% CONFIDENCEin 1.1 yearsClinicalTrials.gov[1] lists 2027-10-18 as the estimated primary completion date; a sponsor's estimate, and trials of this size routinely slip.
Merck & Co.'s phase 3 trial of MK-8527 in human immunodeficiency virus reaches primary completion, the point at which the last participant's primary outcome is measured. The trial enrolled 4,580 participants. Researchers are looking for new medicines to prevent HIV-1 (Human Immunodeficiency Virus Type 1) infection. The goals of this study are to learn: * If taking MK-8527 once a month works to prevent HIV-1 infection better than a standard (usual) pre-exposure prophylaxis (PrEP) taken once a day * About the safety of MK-8527 and if people tolerate it
CONFIRMED87% CONFIDENCE12.1 years agoThe WHO[2] declared the outbreak a public health emergency of international concern on 8 August 2014, following the emergency committee's meeting of 6-7 August.
Eight months after the first cases in Guinea, the WHO declared the Ebola epidemic in West Africa a public health emergency of international concern. It became the largest Ebola outbreak in history: more than 28,000 cases and 11,000 deaths across Guinea, Liberia and Sierra Leone.
CONFIRMED90% CONFIDENCE6.5 years agoThe Director-General used the word at the media briefing of 11 March 2020, the date the WHO's[2] own COVID-19 timeline carries.
Six weeks after declaring a public health emergency, the WHO's Director-General told a Geneva briefing that COVID-19 could be characterised as a pandemic - 118,000 cases in 114 countries at the time. Most of the world's lockdowns began within a fortnight.
ESTIMATED50% CONFIDENCEin 257 daysClinicalTrials.gov[1] lists 2027-06-07 as the estimated primary completion date; a sponsor's estimate, and trials of this size routinely slip.
Sanofi's phase 3 trial of PCV21 Vaccine in pneumococcal immunization reaches primary completion, the point at which the last participant's primary outcome is measured. The trial enrolled 2,195 participants. This is a phase 3 randomized, modified double-blind study whose purpose is to measure whether 3 lots of the investigational pneumococcal vaccine PCV21 can help the body to develop germ-fighting agents called "antibodies" (immunogenicity) in a similar way (ie, same immune response) when they are given to infants aged from approximately 2 months (42 to 89 days) and are safe compared to a licensed 20-valent pneumococcal vaccine (20vPCV) (Prevnar 20™). The study duration per participant will be up to approximately 17 months. The study vaccines (either PCV21 or 20vPCV) will be administered at approximately 2, 4, 6 and 12 months of age. Cohort A will include randomization to three PCV21 formulation groups or one 20vPCV comparator group (Group 1-4, approximately 896 total participants), whereas Cohort B will include randomization to three PCV21 formulation groups only (Groups 1-3, approximately
ESTIMATED50% CONFIDENCEin 1.7 yearsClinicalTrials.gov[1] lists 2028-06-09 as the estimated primary completion date; a sponsor's estimate, and trials of this size routinely slip.
GSK's phase 3 trial of MRNA Seasonal Flu Vaccine in influenza, human reaches primary completion, the point at which the last participant's primary outcome is measured. The trial enrolled 54,000 participants. This study will compare an investigational mRNA flu vaccine with a licensed flu vaccine in adults 65 years of age and older. Participants will receive one injection and will be followed during the flu season. The study will measure prevention of laboratory-confirmed flu illness, side effects, and immune responses.
ESTIMATED50% CONFIDENCEin 2.3 yearsClinicalTrials.gov[1] lists 2028-12-30 as the estimated primary completion date; a sponsor's estimate, and trials of this size routinely slip.
Pfizer's phase 3 trial of PG4 in pneumococcal disease reaches primary completion, the point at which the last participant's primary outcome is measured. The trial enrolled 2,400 participants. The purpose of this study is to learn about the safety of a new pneumococcal vaccine and how the new pneumococcal vaccine helps to fight against germs that can cause pneumonia (lung infections), meningitis (brain infections), and otitis media (ear infections) in infants when compared to the pneumococcal vaccine that is currently in use, 20vPnC (Prevnar 20®). This study will test if the new pneumococcal vaccine is as safe as the one that is currently in use. This new vaccine can possibly provide additional protection against germs that cause pneumococcal disease that are not included in the vaccines that are currently given to infants. Pneumococcal disease includes a variety of infections caused by a specific germ, Streptococcus pneumoniae. There are two groups in this study. All participants will be assigned to one of the two groups. This study is seeking participants who are: \- infants
ESTIMATED50% CONFIDENCEin 1.5 yearsClinicalTrials.gov[1] lists 2028-03-13 as the estimated primary completion date; a sponsor's estimate, and trials of this size routinely slip.
Sanofi's phase 3 trial of MenQuadfi in meningococcal infection reaches primary completion, the point at which the last participant's primary outcome is measured. The trial enrolled 4,568 participants. The purpose of this study is to describe the safety and immunogenicity of MenACYW conjugate vaccine compared with locally-licensed meningococcal vaccines in healthy infants and toddlers in China. Study details include: * Study duration (including 6-month safety follow-up after the last dose): * Cohort I (Groups 1 and 2): approximately 211 or 271 days (approximately 7 or 9 months) * Cohort II (Groups 3 and 4): up to 18 months * Cohort III (Groups 5 and 6): up to 21 months * Cohort III (Group 7): approximately 16 months * Vaccination Visits Period: * Cohort I (Groups 1 and 2): a 2-dose vaccination at V01 (D01) and V02 (D31) or V03 (D91). Two blood samples are collected pre-vaccination (D01) and 30 days post the 2nd dose of vaccination (D61 or D121). Telephone calls (TCs) are planned on the 4th, the 9th, and the 21st day after each vaccination, and 5 TCs (1 TC/month) are planned for the 5 m
ESTIMATED68% CONFIDENCE192 days agoThe source[1] dates the start only to "mid-March 2026", so the pin takes the middle of that month and leaves the end open: the outbreak is ongoing.
A measles outbreak that began in mid-March 2026 has killed 909 people with suspected symptoms and confirmed nearly 20,000 cases, by the Directorate General of Health Services' count as of 10 September. It is still running.
Cambridge Street at Blossom Street, Boston, MA 02114, United StatesMass General Brigham
DELAYED12 months late40% CONFIDENCEin 1.3 yearsMass General Brigham's[1] own page still describes "initial first side of the building opening in 2027", a year earlier than current reporting.
The first of two connected towers in Mass General's Cambridge Street expansion takes its first patients, bringing 450 beds and 12 levels of operating, procedural and interventional space for the Corrigan Minehan Heart Center and the Mass General Cancer Center. Turner topped out the steel in February 2025; the second tower is not due until 2030.
University of Michigan, Ann Arbor, MI 48109, United States
CONFIRMED87% CONFIDENCE71.4 years agoThe field trial results were announced at the University of Michigan on 12 April 1955, the date the announcement itself carries.[1]
At Ann Arbor, Thomas Francis Jr announced the results of the largest medical field trial ever run - 1.8 million children - and pronounced Jonas Salk's polio vaccine safe, effective and potent. Church bells rang across the United States; within two years American cases had fallen by almost 90 per cent.
ESTIMATED73% CONFIDENCEin 189 daysThe IPCC[1][2] reports listing gives the month only — "Special Report Special Report on Climate Change and Cities March 2027" — so the pin sits on the last day of that month, as a month-only date does.
The Intergovernmental Panel on Climate Change delivers the first special report devoted to climate change and cities, due in March 2027. It is one of three special and methodology reports in the AR7 cycle.