Researchers have calculated a key number—the threshold of protection—for other vaccines. Covid-19’s is still a mystery.

Note: The health officials should give a non misleading name to the various Covid-19 “vaccines”

By Jo Craven McGinty

Updated Sept. 10, 2021

Why don’t Covid-19 vaccinations last longer (than 6 months?)?

Measles shots are good for life, chickenpox immunizations protect for 10 to 20 years, and tetanus jabs last a decade or more.

But U.S. officials are weighing whether to authorize Covid-19 boosters for vaccinated adults as soon as six months after the initial inoculation.

The goal of a vaccine is to provide the protection afforded by natural infection, but without the risk of serious illness or death.

“A really good vaccine makes it so someone does not get infected even if they are exposed to the virus,” said Rustom Antia, a biology professor at Emory University who studies immune responses. “But not all vaccines are ideal.”

The three tiers of defense, he said, include full protection against infection and transmission; protection against serious illness and transmission; or protection against serious illness only.

The effectiveness depends on the magnitude of the immune response a vaccine induces, how fast the resulting antibodies decay, whether the virus or bacteria tend to mutate, and the location of the infection.

The threshold of protection is the level of immunity that’s sufficient to keep from getting sick. For every bug, it’s different, and even how it’s determined varies.

Windows of immunity for selected vaccines

Hepatitis A

Human

Papillomavirus

Tetanus

Typhoid

Influenza

Covid-19

0 year

5

10

15

20

Sources: San Francisco Department of Public Health (hepatitis A); National Institutes of Health (human papillomavirus); Centers for Disease Control and Prevention (tetanus, typhoid, influenza, Covid-19)

“Basically, it’s levels of antibodies or neutralizing antibodies per milliliter of blood,” said Mark Slifka, a professor at Oregon Health & Science University.

(T-cells also contribute to protection, but antibodies are easier to measure.)

A threshold 0.01 international units per milliliter was confirmed for tetanus in 1942 when a pair of German researchers intentionally exposed themselves to the toxin to test the findings of previous animal studies.

“One of them gave himself two lethal doses of tetanus in his thigh, and monitored how well it went,” Dr. Slifka said. “His co-author did three lethal doses.”

Neither got sick.

A threshold for measles was pinned down in 1985 after a college dorm was exposed to the disease shortly after a blood drive. Researchers checked antibody concentrations in the students’ blood donations and identified 0.02 international units per milliliter as the level needed to prevent infection.

With these diseases, the magnitudes of response to the vaccines combined with the antibodies’ rates of decay produce durable immune responses: Measles antibodies decay slowly. Tetanus antibodies decay more quickly, but the vaccine causes the body to produce far more than it needs, offsetting the decline.

“We’re fortunate with tetanus, diphtheria, measles and vaccinia,” Dr. Slifka said. “We have identified what the threshold of protection is. You track antibody decline over time, and if you know the threshold of protection, you can calculate durability of protection. With Covid, we don’t know.”

Historically, the most effective vaccines have used replicating viruses, which essentially elicit lifelong immunity.

Measles and chickenpox vaccines use replicating viruses.

Non-replicating vaccines and protein-based vaccines (such as the one for tetanus) don’t last as long, but their effectiveness can be enhanced with the addition of an adjuvant—a substance that enhances the magnitude of the response.

The Johnson & Johnson and AstraZeneca Covid-19 vaccines use non-replicating adenovirus and don’t contain an adjuvant. The Pfizer and Moderna messenger RNA Covid-19 vaccines, which work differently, don’t contain any virus at all. 

Complicating things further, viruses and bacteria that mutate to escape the body’s immune response are harder to control.

Measles, mumps, rubella and chickenpox hardly mutate at all, but at least eight variants of SARS-CoV-2, the virus that causes Covid-19, have been found, according to the British Medical Journal.  

“It does make it more complicated for the vaccine to work,” Dr. Slifka said.

“You’re chasing multiple targets over time. Flu also mutates. With flu, we’ve adjusted by making a new flu vaccine each year that as closely as possible matches the new strain of flu.”

Flu vaccines can offer protection for at least six months.

Setting aside the complexities of crafting an effective vaccine to combat a shape-shifting virus, some hope has revolved around the possibility of defeating Covid-19 by achieving herd immunity, but, according to Dr. Antia, the way coronaviruses infect the body makes that challenging.

“Vaccines are very unlikely to lead to long-lasting herd immunity for many respiratory infections,” Dr. Antia said.

“The herd immunity only lasts for a modest period of time. It depends on how fast the virus changes. It depends on how fast the immunity wanes.”

Part of the problem is that coronaviruses replicate in both the upper and lower respiratory tracts.

“We have good circulation in our lungs and body, but not on the surfaces of our nostrils,” Dr. Slifka said. “We can block severe disease because there are antibodies in the lower respiratory tract.”

But the risk of low-level infections in the upper respiratory tract can persist.

Moving forward, Covid-19 vaccines will be updated to combat variants of the virus, and according to researchers at Imperial College London, the next generation of vaccines might also focus on enhancing immunity in the moist surfaces of the nose and lungs.

In the meantime, avoiding the slippery virus might require another shot.

Finalists Announced for This Year’s National Book Awards

Five books are now shortlisted for each of the five categories: fiction, nonfiction, poetry, translated literature and young people’s literature. Winners will be named in November.

By Elizabeth A. Harris Oct. 5, 2021

A food memoir that examines a mother’s schizophrenia. A novel about an author’s book tour, and about growing up as a Black boy in the rural South. Poetry honoring migrants who drowned while trying to cross the Rio Grande.

These are some of the 25 finalists for the National Book Awards, which the National Book Foundation announced on Tuesday.

In “Tastes Like War: A Memoir,” by Grace M. Cho, the author cooks her grandmother’s recipes while exploring her mother’s illness, and how war, colonialism and xenophobia live on in the body.

Other nonfiction nominees include “Covered With Night: A Story of Murder and Indigenous Justice in Early America,” by Nicole Eustace, which examines the 1722 murder case of an Indigenous hunter, and

“A Little Devil in America: Notes in Praise of Black Performance,” whose author, the poet Hanif Abdurraqib, received a MacArthur Fellowship last month.

The book-tour novel is “Hell of a Book,” by Jason Mott, who was joined in the fiction category by two authors who have been previously shortlisted for the National Book Award: Anthony Doerr, this time for “Cloud Cuckoo Land,” and Lauren Groff for “Matrix.” “Matrix” follows Marie de France, a “bastardess sibling of the crown,” as she transforms a destitute nunnery, all but forgotten and plagued by starvation, into a wealthy and powerful world of women.

“Bewilderment,” by the Pulitzer Prize winner Richard Powers, and “The Love Songs of W.E.B. Du Bois,” by Honorée Fanonne Jeffers, two best-selling novels that made the longlist when it was announced in September, are not among the finalists.

In the poetry category, it is Martín Espada who honors migrants who drowned in the Rio Grande in his book “Floaters.” In “What Noise Against the Cane,” Desiree C. Bailey explores the Haitian Revolution and what it means to be a Black woman in the United States today.

National Book Awards finalists include, from left:

Tiya Miles for nonfiction; Jackie Wang for poetry; Robert Jones Jr. for fiction; Shing Yin Khor for young people’s literature; and Benjamín Labatut for translated literature.

Credit…From left: Kimberly P. Mitchell/USA Today Network; Nightboat Books; Alberto Vargas/RainRiver Images; Shing Yin Khor; Juana Gómez

In the category of translated literature, Benjamín Labatut’s book “When We Cease to Understand the World” is among the finalists. Translated from Spanish by Adrian Nathan West, the novel imagines the lives of renowned scientists like the Nobel Prize-winning physicist Erwin Schrödinger. Its competition includes “Planet of Clay,” by Samar Yazbek, translated from Arabic by Leri Price, which follows a girl named Rima during the Syrian Civil War.

“The Legend of Auntie Po,” a graphic novel by Shing Yin Khor, is a finalist for young people’s literature. The novel reimagines the story of Paul Bunyan against the backdrop of race and immigration in the period following the Chinese Exclusion Act of 1882. “Revolution in Our Time: The Black Panther Party’s Promise to the People,” Kekla Magoon’s book connecting the Black Panther Party to the Black Lives Matter movement, is also a finalist.

The winners in young people’s literature, translated literature, poetry, nonfiction and fiction will be announced Nov. 17 in an online ceremony.

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Two lifetime achievement awards will also be presented. The writer and professor Karen Tei Yamashita will receive the foundation’s Medal for Distinguished Contribution, and the author and librarian Nancy Pearl will be given the Literarian Award for Outstanding Service to the American Literary Community.

Below is a complete list of the finalists.

Fiction

• Anthony Doerr, “Cloud Cuckoo Land”
• Lauren Groff, “Matrix”
• Laird Hunt, “Zorrie”
• Robert Jones Jr., “The Prophets”
• Jason Mott, “Hell of a Book”

Nonfiction

• Hanif Abdurraqib, “A Little Devil in America: Notes in Praise of Black Performance”
• Lucas Bessire, “Running Out: In Search of Water on the High Plains”
• Grace M. Cho, “Tastes Like War: A Memoir”
• Nicole Eustace, “Covered With Night: A Story of Murder and Indigenous Justice in Early America”
• Tiya Miles, “All That She Carried: The Journey of Ashley’s Sack, a Black Family Keepsake”

Poetry

• Desiree C. Bailey, “What Noise Against the Cane”
• Martín Espada, “Floaters”
• Douglas Kearney, “Sho”
• Hoa Nguyen, “A Thousand Times You Lose Your Treasure”
• Jackie Wang, “The Sunflower Cast a Spell to Save Us From the Void”

Translated Literature

• Elisa Shua Dusapin, “Winter in Sokcho”
  Translated from the French by Aneesa Abbas Higgins
• Ge Fei, “Peach Blossom Paradise”
  Translated from the Chinese by Canaan Morse
• Nona Fernández, “The Twilight Zone”
  Translated from the Spanish by Natasha Wimmer
• Benjamín Labatut, “When We Cease to Understand the World”
  Translated from the Spanish by Adrian Nathan West
• Samar Yazbek, “Planet of Clay”
  Translated from the Arabic by Leri Price

Young People’s Literature

• Shing Yin Khor, “The Legend of Auntie Po”
• Malinda Lo, “Last Night at the Telegraph Club”
• Kyle Lukoff, “Too Bright to See”
• Kekla Magoon, “Revolution in Our Time: The Black Panther Party’s Promise to the People”
• Amber McBride, “Me (Moth)”

Elizabeth A. Harris writes about books and publishing. @Liz_A_Harris