diff --git a/go.mod b/go.mod
index 8a40c46..f088985 100644
--- a/go.mod
+++ b/go.mod
@@ -25,7 +25,6 @@
 	golang.org/x/exp/event v0.0.0-20220218215828-6cf2b201936e
 	golang.org/x/mod v0.7.0
 	golang.org/x/net v0.7.0
-	golang.org/x/sync v0.1.0
 	golang.org/x/tools v0.5.1-0.20230117180257-8aba49bb5ea2
 	golang.org/x/vuln v0.0.0-20230201222900-4c848edceff1
 	google.golang.org/api v0.110.0
@@ -58,6 +57,7 @@
 	go.opentelemetry.io/otel/trace v1.11.2 // indirect
 	golang.org/x/exp/typeparams v0.0.0-20221208152030-732eee02a75a // indirect
 	golang.org/x/oauth2 v0.5.0 // indirect
+	golang.org/x/sync v0.1.0 // indirect
 	golang.org/x/sys v0.5.0 // indirect
 	golang.org/x/text v0.7.0 // indirect
 	golang.org/x/xerrors v0.0.0-20220907171357-04be3eba64a2 // indirect
diff --git a/internal/vulndb/vulndb.go b/internal/vulndb/vulndb.go
index 6fa62fd..9f9d1df 100644
--- a/internal/vulndb/vulndb.go
+++ b/internal/vulndb/vulndb.go
@@ -7,9 +7,11 @@
 package vulndb
 
 import (
+	"context"
 	"time"
 
 	"golang.org/x/pkgsite-metrics/internal/bigquery"
+	"golang.org/x/pkgsite-metrics/internal/derrors"
 	"golang.org/x/vuln/osv"
 )
 
@@ -107,3 +109,26 @@
 	}
 	return rs
 }
+
+// ReadMostRecentDB returns entries from the table that reflect the
+// most recent state of the vulnerability database at c.
+func ReadMostRecentDB(ctx context.Context, c *bigquery.Client) (entries []*Entry, err error) {
+	defer derrors.Wrap(&err, "ReadMostRecentDB")
+	query := bigquery.PartitionQuery{
+		Table:       c.FullTableName(TableName),
+		PartitionOn: "ID",
+		OrderBy:     "modified_time DESC",
+	}.String()
+	iter, err := c.Query(ctx, query)
+	if err != nil {
+		return nil, err
+	}
+	err = bigquery.ForEachRow(iter, func(e *Entry) bool {
+		entries = append(entries, e)
+		return true
+	})
+	if err != nil {
+		return nil, err
+	}
+	return entries, nil
+}
diff --git a/internal/vulndb/vulndb_test.go b/internal/vulndb/vulndb_test.go
index 6c86f73..adc07df 100644
--- a/internal/vulndb/vulndb_test.go
+++ b/internal/vulndb/vulndb_test.go
@@ -5,9 +5,13 @@
 package vulndb
 
 import (
+	"context"
 	"testing"
+	"time"
 
 	"github.com/google/go-cmp/cmp"
+	"golang.org/x/pkgsite-metrics/internal/bigquery"
+	test "golang.org/x/pkgsite-metrics/internal/testing"
 	"golang.org/x/vuln/osv"
 )
 
@@ -36,3 +40,46 @@
 		t.Fatalf("mismatch (-want, +got):\n%s", diff)
 	}
 }
+
+func TestReadMostRecentDB(t *testing.T) {
+	test.NeedsIntegrationEnv(t)
+
+	ctx := context.Background()
+	const projectID = "go-ecosystem"
+
+	client, err := bigquery.NewClientForTesting(ctx, projectID)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer client.Close()
+
+	writeToBigQuery := func(es []*Entry) {
+		if err := client.CreateTable(ctx, TableName); err != nil {
+			t.Fatal(err)
+		}
+		if err := bigquery.UploadMany(ctx, client, TableName, es, 0); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	lmt := time.Now()
+	es := []*Entry{
+		{ID: "A"},
+		{ID: "A", ModifiedTime: lmt},
+		{ID: "B", ModifiedTime: lmt},
+	}
+	writeToBigQuery(es)
+
+	got, err := ReadMostRecentDB(ctx, client)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(got) != 2 {
+		t.Fatalf("want 2 rows; got %d", len(got))
+	}
+	for _, e := range got {
+		if e.ModifiedTime != lmt {
+			t.Fatalf("want last modified time %v; got %v", lmt, e.ModifiedTime)
+		}
+	}
+}
diff --git a/internal/worker/vulndb.go b/internal/worker/vulndb.go
index 47a1b01..0ee62e2 100644
--- a/internal/worker/vulndb.go
+++ b/internal/worker/vulndb.go
@@ -11,6 +11,7 @@
 	"os"
 	"path/filepath"
 	"strings"
+	"time"
 
 	"fmt"
 	"net/http"
@@ -22,6 +23,7 @@
 	"golang.org/x/pkgsite-metrics/internal"
 	"golang.org/x/pkgsite-metrics/internal/bigquery"
 	"golang.org/x/pkgsite-metrics/internal/derrors"
+	"golang.org/x/pkgsite-metrics/internal/log"
 	"golang.org/x/pkgsite-metrics/internal/vulndb"
 	"golang.org/x/pkgsite-metrics/internal/vulndbreqs"
 )
@@ -66,12 +68,28 @@
 	if bucket == nil {
 		return errors.New("failed to create go-vulndb bucket")
 	}
+
+	lmts, err := lastModified(ctx, dbClient)
+	if err != nil {
+		return err
+	}
 	entries, err := vulndbEntries(ctx, bucket)
 	if err != nil {
 		return err
 	}
+	for _, e := range entries {
+		lmt, ok := lmts[e.ID]
+		if ok && e.ModifiedTime.Equal(lmt) {
+			// Skip adding the entry if nothing has changed in the meantime.
+			log.Infof(ctx, "skipping entry %s, it has not been modified", e.ID)
+			continue
+		}
+		if err = writeResult(ctx, false, w, dbClient, vulndb.TableName, e); err != nil {
+			return err
+		}
+	}
 
-	return bigquery.UploadMany(ctx, dbClient, vulndb.TableName, entries, 10000)
+	return nil
 }
 
 func vulndbEntries(ctx context.Context, bucket *storage.BucketHandle) ([]*vulndb.Entry, error) {
@@ -132,3 +150,15 @@
 	}
 	return &entry, nil
 }
+
+func lastModified(ctx context.Context, c *bigquery.Client) (map[string]time.Time, error) {
+	es, err := vulndb.ReadMostRecentDB(ctx, c)
+	if err != nil {
+		return nil, err
+	}
+	m := make(map[string]time.Time)
+	for _, e := range es {
+		m[e.ID] = e.ModifiedTime
+	}
+	return m, nil
+}