In an essay in the New York Times Sunday Review for February 6th, 2022 entitled “How Does a Pandemic End?”, John M. Barry, author of a book on the history of the Spanish Flu Pandemic of 1918-1920: The Great Influenza : The Story of the Deadliest Pandemic in History, writes of the “fourth wave” of this pandemic which hit the United States in 1920:
A variant that emerged in 1920 was lethal enough that it should have counted as a fourth wave. In some cities—among them, Detroit, Milwaukee, Minneapolis and Kansas City, MO—deaths exceeded even those in the second wave [fall of 1918], responsible for the vast majority of the pandemic’s deaths in the United States and elsewhere. This occurred even though the U.S. population had plenty of natural immunity from the influenza virus after two years of infection and after viral lethality in the third wave [winter of 1919] decreased.
Nearly all cities in the United States imposed restrictions during the pandemic’s virulent second wave, which peaked in the fall of 1918. That winter, some cities re-imposed controls when a third, though less deadly, wave struck. But virtually no city responded in 1920. People were weary of influenza and so were public officials. Newspapers were filled with frightening news about the virus, but no-one cared. People at the time ignored this fourth wave; so did historians. Deaths returned to pre-pandemic levels in 1921, and the virus mutated into ordinary seasonal influenza, but the world had moved on well before.
The reference to this forgotten “fourth wave” struck a chord with me because of one of the life-stories in my own family tree: Matthew and Mary Higgins, a great uncle and aunt, who were carried off by this flu within 9 days of each other in February, 1920, leaving two orphaned sons, Joe and Charlie.
Boston’s newspapers on February 16th carried the headline news story of the death of Matthew J. Higgins, president of the Boston Carmen’s Union, of influenza, nine days after his wife.
Matthew J. Higgins, who was serving his fifth term as president of Boston’s Street Carmen’s Union, died at his home, 44 Weld St., Jamaica Plain, shortly after noon yesterday, after a week’s illness from influenza.
He leaves two children, Joseph, aged 3, and Charles, 6 months. His wife died a week ago yesterday after a short illness from the same disease. He was stricken shortly before her funeral and was confined to his bed while her burial was being held. 

[He was not yet 40 years old. He was one of my great-grandfather Jeremiah Higgins’s younger brothers. They had emigrated from Cork, Ireland, as children with their parents in 1890, and settled in Pittsfield, MA.]
Mr. Higgins was one of the best known leaders of organized labor in the country...Some years ago he came to this city and obtained employment as a conductor with the Boston Elevated, being attached to the Jamaica Plain, Roxbury and Brookline stations during his entire period of service. He was elected president after the 1912 strike and, with the exception of three terms has held the office since. He was recently re-elected by an overwhelming vote.
The executive board of the Boston Street Carmen’s Union, the members of which had gathered yesterday afternoon to attend the funeral of Henry B. Endicott, decided to postpone the special election of a new secretary...When it was reported at the meeting of the Boston Central Labor Union yesterday afternoon that President Higgins had died, the delegates suspended business and stood with bowed heads for one minute in respect for his memory. —Boston Traveler

He was one of the best known members of organized labor in the country, despite the fact that he has been affiliated with unionism for a comparatively brief period, since the organization of the Boston Elevated employees as the Boston Street Carmen’s Union, Local 589. Known as a conservative in the labor movement, he had nevertheless led the organization to many brilliant victories, the most recent being the wage increase granted the men last summer, making them among the highest paid street carmen in the country. —Boston Post
Matthew Higgins was buried with a Requiem Mass out of St. Andrew’s Church in Forest Hills and laid to rest beside his wife, Mary, at Mount Calvary Cemetery.

Of the two orphaned boys Joe and Charlie, the baby was also sick with the flu and not expected to live. He did, however, survive. The boys’ maternal grandfather, a widower, decided to adopt them himself. He hired a nanny to help him take care of them and, eventually, he married the nanny.
The brothers Joe and Charlie Higgins grew and lived out their lives in Boston, dying in their old age. They too are buried in Mount Calvary Cemetery.