sciencemag.org SCIENCEPHOTO: GASTON BRITO/GETTY IMAGESNEWSU.S. is far from herd immunity
COVID-19 | Fewer than one in
10 Americans carried antibodies to the
pandemic coronavirus in late July,
according to a nationwide study of
dialysis patients. One of the largest of its
kind, the study indicates that the United
States is a long way from reaching “herd
immunity” to COVID-19, when a large
portion of the population would become
resistant to the virus that causes the
disease, slowing the rate of new infec-
tions. Researchers reported last week in
The Lancet that they found the virus in
8% of samples from leftover plasma of
28,503 people. Residents of neighbor-
hoods that are predominantly Black or
Hispanic or are densely populated were
significantly more likely to have antibod-
ies to the virus. The researchers also
found regional differences: Thirty-three
percent of New York state samples had
antibodies, but only 3.8% of California
samples did.
IN BRIEF
Edited by Jeffrey BrainardThe global toll of COVID-19 this week passed 1 million deaths. A mourner cries near where a relative was laid to rest at the Cementerio General in La Paz, Bolivia.
This summer, the cemetery saw as many as 90 burials per day and built three new pavilions and two mass graves.
14 2 OCTOBER 2020 • VOL 370 ISSUE 6512
Trump wants shorter student visas
IMMIGRATION | The Trump administra-
tion last week proposed tightening visa
policies for international students, a
step it says is necessary to monitor their
academic progress and protect national
security. But many university officials
believe the new rules, if adopted, would
reinforce the message that foreign stu-
dents aren’t welcome. One change would
impose a 4-year limit on their stay; a visa
is now good for the duration of a stu-
dent’s academic program. And the limit
would only be 2 years for students from
59 countries where more than 10% of visa
holders violate the terms of their visit.
The 4-year limit would apply to students
from China and India, which combined
are home to more than half the total
number of international students in the
United States. Any student wanting to
remain to complete a degree would need
to have “a compelling academic reason” or
face “circumstances beyond their control.”Even if finalized, however, the changes are
unlikely to take effect if President Donald
Trump loses the November election.Genome gaps nearly filled
GENETICS | Despite the fanfare that
greeted the first human genome sequence
17 years ago, researchers knew it was in-
complete. For the sake of speed and because
of limitations in technology, teams had
skipped over regions of nearly identical
DNA, which are difficult to map correctly.
Last week, using newer technologies, a
team of 70 researchers released a human
cell line’s genome sequence with almost all
those difficult parts deciphered. It’s a first
attempt to sequence each chromosome from
telomere to telomere, meaning from one
end to the other. The work fills in about
135 million missing base pairs, bringing the
total to 3.057 billion bases, the Telomere-to-
Telomere consortium announced on Twitter
and in the Genome Informatics Section of
GitHub. Still missing are arrays of genes