Since December, 2019, the outbreak of the 2019 novel coronavirus disease (COVID-19)
infection has become a major epidemic threat in China. As of Feb 11, 2020, the cumulative
number of confirmed cases in mainland China has reached 38 800, with 4740 (12·2%)
cured cases and 1113 (2·9%) deaths; additionally, there have been 16 067 suspected
cases so far.
1
All 31 provinces in mainland China have now adopted the first-level response to major
public health emergencies. The National Health Commission of China has published a
series of guidelines on the prevention, diagnosis, and treatment of COVID-19 pneumonia,
based on growing evidence of the pathogens responsible for COVID-19 infection, as
well as the epidemiological characteristics, clinical features, and the most effective
treatments.2, 3, 4 The central government and some provincial governments have provided
food and medical supplies and dispatched expert groups and medical teams to manage
and control the outbreak response in the hardest-hit areas (Wuhan and neighbouring
cities in Hubei province).
As the COVID-19 outbreak unfolds, prevention and control of COVID-19 infection among
pregnant women and the potential risk of vertical transmission have become a major
concern. More evidence is needed to develop effective preventive and clinical strategies.
The latest research by Huijun Chen and colleagues
5
reported in The Lancet provides some insight into the clinical characteristics, pregnancy
outcomes, and vertical transmission potential of COVID-19 infection in pregnant women.
Although the study analysed only a small number of cases (nine women with confirmed
COVID-19 pneumonia), under such emergent circumstances these findings are valuable
for preventive and clinical practice in China and elsewhere. Although neonatal nasopharyngeal
swab samples have been collected in some hospitals across China, this study also collected
and tested amniotic fluid, cord blood, and breastmilk samples for the presence of
severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), thus allowing a more
detailed assessment of the vertical transmission potential of COVID-19 infection.
SARS-CoV-2 is a new strain of coronaviruses that are pathogenic to humans. Another
two notable strains are SARS-CoV and the Middle East respiratory syndrome (MERS) coronavirus
(MERS-CoV). A study done by Roujian Lu and colleagues
6
found that although SARS-CoV-2 is genetically closer to two bat-derived SARS-like
coronaviruses, bat-SL-CoVZC45 and bat-SL-CoVZXC21 (with about 88% genome sequence
identity), than to SARS-CoV-1 (about 79% identity) and MERS-CoV (about 50% identity),
homology modelling has revealed that SARS-CoV-2 has a similar receptor-binding domain
structure to that of SARS-CoV-1, which suggests that COVID-19 infection might have
a similar pathogenesis to SARS-CoV-1 infection.6, 7, 8 Thus, the risk of vertical
transmission of COVID-19 might be as low as that of SARS-CoV-1. The present study
by Chen and colleagues did not find any evidence of the presence of SARS-CoV-2 viral
particles in the products of conception or in neonates, in accordance with the findings
of a previous study on SARS-CoV-1 done by Wong and colleagues.
9
Two neonatal cases of COVID-19 infection have been confirmed so far,
10
with one case confirmed at 17 days after birth and having a close contact history
with two confirmed cases (the baby's mother and maternity matron) and the other case
confirmed at 36 h after birth and for whom the possibility of close contact history
cannot be excluded. However, no reliable evidence is as yet available to support the
possibility of vertical transmission of COVID-19 infection from the mother to the
baby.
© 2020 Soe Zeya Tun/Reuters
2020
Since January 2020 Elsevier has created a COVID-19 resource centre with free information
in English and Mandarin on the novel coronavirus COVID-19. The COVID-19 resource centre
is hosted on Elsevier Connect, the company's public news and information website.
Elsevier hereby grants permission to make all its COVID-19-related research that is
available on the COVID-19 resource centre - including this research content - immediately
available in PubMed Central and other publicly funded repositories, such as the WHO
COVID database with rights for unrestricted research re-use and analyses in any form
or by any means with acknowledgement of the original source. These permissions are
granted for free by Elsevier for as long as the COVID-19 resource centre remains active.
Previous studies have shown that SARS during pregnancy is associated with a high incidence
of adverse maternal and neonatal complications, such as spontaneous miscarriage, preterm
delivery, intrauterine growth restriction, application of endotracheal intubation,
admission to the intensive care unit, renal failure, and disseminated intravascular
coagulopathy.9, 11 However, pregnant women with COVID-19 infection in the present
study had fewer adverse maternal and neonatal complications and outcomes than would
be anticipated for those with SARS-CoV-1 infection. Although a small number of cases
was analysed and the findings should be interpreted with caution, the findings are
mostly consistent with the clinical analysis done by Zhu and colleagues
12
of ten neonates born to mothers with COVID-19 pneumonia. The clinical characteristics
reported in pregnant women with confirmed COVID-19 infection are similar to those
reported for non-pregnant adults with confirmed COVID-19 infection in the general
population and are indicative of a relatively optimistic clinical course and outcomes
for COVID-19 infection compared with SARS-CoV-1 infection.13, 14
Nonetheless, because of the small number of cases analysed and the short duration
of the study period, more follow-up studies should be done to further evaluate the
safety and health of pregnant women and newborn babies who develop COVID-19 infection.
As discussed in the study, pregnant women are susceptible to respiratory pathogens
and to development of severe pneumonia, which possibly makes them more susceptible
to COVID-19 infection than the general population, especially if they have chronic
diseases or maternal complications. Therefore, pregnant women and newborn babies should
be considered key at-risk populations in strategies focusing on prevention and management
of COVID-19 infection. Based on evidence from the latest studies and expert recommendations,
as well as previous experiences from the prevention and control of SARS, the National
Health Commission of China launched a new notice on Feb 8, 2020,
15
which proposed strengthening health counselling, screening, and follow-ups for pregnant
women, reinforcing visit time and procedures in obstetric clinics and units with specialised
infection control preparations and protective clothing, and emphasised that neonates
of pregnant women with suspected or confirmed COVID-19 infection should be isolated
in a designated unit for at least 14 days after birth and should not be breastfed,
to avoid close contact with the mother while she has suspected or confirmed COVID-19
infection.
We need to further strengthen our capacity to deal with emergent infectious disease
outbreaks, through laws and regulations to prevent and control the spread of infectious
diseases and to avoid outbreak clusters in families, communities, and other public
places, and to do so with transparency and solidarity. Timely reporting and disclosure
of emergent infectious diseases is also important to avoid delayed responses. Infection
control and management procedures in hospitals and other places with several confirmed
cases isolated together should also be maintained, and specialised clothing and equipment
provided to protect medical professionals and other health workers from occupational
exposure to COVID-19 infection.