[citation needed] In 1881, Pfizer moved its administrative headquarters to 81 Maiden Lane in Manhattan, presaging the company's expansion to Chicago, Illinois a year later.

Pfizer imported the compound from Italy for the manufacture of citric acid, and due to the disruption in supply, the company began a search for an alternative.

These skills were applied to the deep-submergence mass production of penicillin, an antibiotic, during World War II in response to the need to treat injured Allied soldiers.

[13] The company also embarked on a global soil collection program related to improving production yields of penicillin which ultimately resulted in 135,000 samples.

[11] As the area surrounding its Brooklyn, NY plant fell into decline in the 1970s and 1980s, the company formed a public-private partnership with New York City that encompassed the construction of low- and middle-income housing, the refurbishment of apartment buildings for the homeless and the establishment of a charter school.

[15] In 1986, Pfizer acquired the worldwide rights to Zithromax (azithromycin), a macrolide antibiotic that is recommended by the Infectious Disease Society of America as a first line treatment for certain cases of community-acquired pneumonia, from Pliva.

[16][17] In 1989, Pfizer scientists Peter Dunn and Albert Wood created Viagra (sildenafil) for treating high blood pressure and angina, a chest pain associated with coronary artery disease.

[25] In 2001, Henry McKinnell became chief executive officer of the company, replacing William C. Steere, Jr.[26] In 2002, The Bill & Melinda Gates Foundation purchased stock in Pfizer.

[27] In 2004, the company received approval for Lyrica (pregabalin), an anticonvulsant and anxiolytic medication used to treat epilepsy, neuropathic pain, fibromyalgia, restless leg syndrome, and generalized anxiety disorder.

[26][32] On December 3, 2006, Pfizer ceased development of torcetrapib, a drug that increases production of HDL, which reduces LDL thought to be correlated to heart disease.

Pfizer has hired customs and narcotics experts worldwide to track down fakes and assemble evidence that can be used to pursue civil suits for trademark infringement.

The introduction of the original, 7-valent version of the vaccine, developed by Wyeth in February 2000, led to a 75% reduction in the incidence of invasive pneumococcal infections among children under age 5 in the United States.

[56] In February 2011, Pfizer announced the closure of its UK research and development facility (formerly also a manufacturing plant) in Sandwich, Kent, which at the time employed 2,400 people.

[85][86][87] On April 6, 2016, Pfizer and Allergan terminated the merger agreement after the Obama administration and the United States Department of the Treasury introduced new laws intended to limit corporate inversions (the extent to which companies could move their headquarters overseas in order to reduce the amount of taxes they pay).

[121][122] CEO Albert Bourla attended the GAVI COVAX AMC 2021 Investment Opportunity Launch Event, otherwise named One World Protected, on April 15, 2021.

[127] The company began Phase II-III testing on 30,000 people in the last week of July 2020 and was slated to be paid $1.95 billion for 100 million doses of the vaccine by the US government.

"[144] On 10 October 2022, during a session of the European Parliament's Special Committee on the COVID-19 Pandemic, Pfizer executive Janine Small testified that the company had not evaluated their COVID-19 vaccine for its ability to reduce transmission of the SARS-CoV-2 virus prior to its release to the general public.

[153] U.S. President Joe Biden and Dr. Anthony Fauci were both reported to experience this rebound syndrome in the months that followed, while continuing to recommend the drug for those who may benefit from it.

[197][198] According to the lawsuit, Pfizer handed out 'misleading' materials on off-label uses, sent over 5,000 doctors on trips to the Caribbean or around the United States, and paid them $2,000 honoraria in return for listening to lectures about Bextra.

[205] A judge dismissed the case citing a lack of evidence that the illness was caused by the virus but the jury ruled that by firing the employee, Pfizer violated laws protecting freedom of speech and whistleblowers and awarded her $1.37 million.

Pfizer representatives and personnel from a contract research organization (CRO) traveled to Kano to set up a clinical trial and administer an experimental antibiotic, trovafloxacin, to approximately 200 children.

[208] Tests in animals showed that Trovan had life-threatening side effects, including joint disease, abnormal cartilage growth, liver damage, and a degenerative bone condition.

[209] Local Kano officials reported that more than fifty children died in the experiment, while many others developed mental and physical deformities such as blindness, deafness, paralysis, and brain damage.

"[213] The lawsuits also accused Pfizer of using the outbreak to perform unapproved human testing, as well as allegedly under-dosing a control group being treated with traditional antibiotics in order to skew the results of the trial in favor of Trovan.

Trovan had been used safely in more than five thousand Americans prior to the Nigerian trial, and mortality in the patients treated by Pfizer was lower than that observed historically in African meningitis epidemics.

[217] In December 2010, the United States diplomatic cables leak indicated that Pfizer hired investigators to find evidence of corruption against Nigerian attorney general Michael Aondoakaa to persuade him to drop legal action.

[219] Aondoakka, who had allegedly demanded bribes from Pfizer in return for a settlement of the case,[220] was declared unfit for office and had his U.S. visa revoked in association with corruption charges in 2010.

[223] In July 2022, UK antitrust authorities fined Pfizer £63 million for unfairly high priced drug that aids in controlling epileptic seizures.

[228] The Sierra Club and the Edison Wetlands Association have opposed the cleanup plan, arguing that the area is subject to flooding, which could cause pollutants to leach.

[230] Pfizer engages with the public and private sectors in a variety of settings including to promote research and development, academic funding, event sponsorship, philanthropy, and political lobbying.