1422 17 DECEMBER 2021 • VOL 374 ISSUE 6574 science.org SCIENCE
India defuses
its population
bomb
Sterilization, contraceptives
push fertility rate down
to two children per woman
POPULATIONB
ack in the 1960s, India faced an
exploding population, with a fertil-
ity rate of nearly six children per
woman. When famine struck, U.S.
President Lyndon B. Johnson ini-
tially refused to deliver food aid,
citing the country’s high birth rate. In
response, India’s Prime Minister Indira
Gandhi dramatically expanded the first
national family planning program in a
major developing country, offering cash
incentives for both men and women to be
sterilized. The city of Madras, now called
Chennai, paid men $6 a snip.
For the next 60 years, India continued to
focus on sterilization as well as contracep-
tives and education for girls. Now, Indian
health officials say the task of defusing
their population bomb is finally done. Late
last month, the National Family Health
Survey (NFHS), a periodic investigation
of half a million households, announced a
milestone: The country’s fertility rate had
for the first time fallen below the widely
accepted “replacement level” of 2.1 chil-
dren per woman. (The U.S. rate is 1.8.)
“Women are seeing the wisdom in having
fewer children,” says Poonam Muttreja, di-
rector of the nonprofit Population Founda-
tion of India.
India’s population growth is not over
yet, however. Thanks to past high fertility
rates, two-thirds of the population is under
35 years old, and a large cohort of people
is now entering childbearing age. Even at
replacement fertility rates, the children of
these young people will continue to push
up numbers, and India may exceed China
as the world’s most populous nation as
early as next year.
Still, India’s population is set to decline
in about 3 decades, putting the country
on the same track as a growing number of
developing nations, such as its neighbor
Bangladesh and Indonesia. India remains
well behind China in falling fertility. InBy Fred Pearcelate night work, and little sleep. “We have
people working the whole weekend again,”
says Florian Krammer, a vaccine researcher
at the Icahn School of Medicine at Mount
Sinai. “It doesn’t matter if something needs
to be done at 10 p.m., it’s getting done.”
As with earlier variants, a handful of
countries are providing the world with
most of the early data. South Africa, where
scientists first observed the spread of Omi-
cron, has sequenced a wealth of genomes
and produced data about early cases. Den-
mark, with one of the best genomic surveil-
lance systems in the world, has provided an
in-depth view of how Omicron can explode
on top of a Delta surge. And scientists in
the United Kingdom are conducting a host
of studies to nail down how well Omicron
transmits in households and elsewhere, and
how vaccines are doing against the vari-
ant. “We should be pretty grateful” to these
countries, Hodcroft says.
As a result, Omicron’s key properties
are becoming clearer by the day. It’s be-
yond doubt that the variant has a substan-
tial growth advantage. What’s less clear is
whether that’s mostly because it can evade
the human immune response or also be-
cause it is inherently more transmissible
than its predecessors. That may not matter
in the short run, but it does for the long-
term outlook. If it’s all about immune eva-
sion, Omicron’s advantage over Delta could
wane as immunity to it builds up, and the
two could end up cocirculating. If Omicron
is also more infectious, it may replace Delta,
just as Delta displaced earlier variants.
How good Omicron is at immune escape
is also becoming clearer. Preliminary data
from South Africa showed its rise coincided
with an unexpected surge in reinfections.
This past week, laboratory assays by several
groups have shown antibodies, whether
elicited by vaccines or a previous infection,
are significantly less effective at neutraliz-
ing Omicron than other variants. And based
on the first cases, scientists in the United
Kingdom have estimated that protection
from symptomatic illness is much lower in
people who have received two doses of the
AstraZeneca or messenger RNA vaccines.
The good news is that boosters appear
to bring protection against disease back
to about 75%, and probably even higher
against hospitalization. “I think it all boils
down in the end to protection from severe
disease,” Krammer says.
Early data from Discovery, South Africa’s
largest health insurer, presented on 14 De-
cember, offered some additional reassur-
ance that Omicron’s immune escape isn’t
complete. The data showed hospital ad-
missions in the country are growing more
slowly than in previous waves. That could
mean the protection from severe disease
is still robust in vaccinated and recovered
people—or the virus is inherently a bit
milder than Delta.
But Harvard University epidemiologist
William Hanage says the question of severity
is still impossible to answer. Recent genomic
comparisons suggest Omicron only began
to spread in mid-October—earlier work had
estimated late September—so the variant
hasn’t infected enough people to conclude
much of anything, he says. By chance, many
of the early cases in South Africa happened
to be in younger people, who are less likely
to develop severe disease. And even if the
variant turns out to be inherently milder, the
volume of cases will likely overwhelm health
systems. “A colleague put it really well in
one of our little depressing Slack channels,”
Hanage says: “There’s not much that can
spread this fast and be benign to a society
that’s already got full hospitals without it.”
Scientists also worry Omicron—which rep-
resented a massive leap from known variants
in genomic terms—may bring other, unpleas-
ant evolutionary surprises. For instance,
roughly one-tenth of Omicron genomes se-
quenced so far have an additional mutation
in the spike protein called 346K that is pre-
dicted to make it even better at evading the
immune system. “Omicron has most of the
greatest hits for antibody escape already, so
there aren’t a ton of additions that it could
make, but 346K is one of them,” says Stephen
Goldstein, a virologist at the University of
Utah. “We have to keep an eye on it.”
Given its divergence from earlier vari-
ants, Krammer thinks vaccine manu-
facturers should develop booster shots
tailored to Omicron. Obtaining regulatory
approval and making such boosters avail-
able in large numbers would take months,
however—too long to address the crisis
many scientists expect. And if the past
year is any indicator, they are unlikely to
be available to low- and middle-income
countries in any meaningful quantities.
For now, most European countries are
hoping that providing existing boost-
ers widely, in tandem with added control
measures such as a ban on large gather-
ings, mask mandates, better ventilation,
and working from home, will help lower
the wave of Omicron infections and pre-
vent hospitals from buckling. Maria Van
Kerkhove, an epidemiologist at the World
Health Organization, says vaccinating those
who have not received any shots at all is still
very important—even though it may be too
late to get the numbers up substantially.
“Get the vaccine into the arms of people
who are most at risk,” Van Kerkhove says.
“Look to see who you’re missing and focus
on these.” jNEWS | IN DEPTH